#include <bits/stdc++.h>
class Scanner {
 private:
  static const int BUFFER_SIZE = 1 << 18;
  char buff[BUFFER_SIZE];
  char *buffPos, *buffLim;
  FILE* file;

 public:
  Scanner(FILE* file) {
    this->file = file;
    buffLim = buff + fread(buff, 1, BUFFER_SIZE, file);
    buffPos = buff;
  }

 private:
  inline void flushBuff() {
    buffLim = buff + fread(buff, 1, BUFFER_SIZE, file);
    if (buffLim == buff) {
      *buffLim++ = '\n';
    }
    buffPos = buff;
  }
  inline bool isWS(char t) { return t <= ' '; }
  inline bool isDig(char t) { return t >= '0' && t <= '9'; }
  inline void nextPos() {
    buffPos++;
    if (buffPos == buffLim) {
      flushBuff();
    }
  }

 public:
  inline char getchar() {
    char ch = *buffPos;
    nextPos();
    return ch;
  }
  inline void next(char* s) {
    while (isWS(*buffPos)) {
      nextPos();
    }
    while (!isWS(*buffPos)) {
      *s = *buffPos;
      s++;
      nextPos();
    }
    *s = '\0';
  }
  inline void nextLine(char* s) {
    while (*buffPos != '\n') {
      nextPos();
    }
    if (*buffPos == '\n') {
      nextPos();
    }
    while (*buffPos != '\n') {
      *s++ = *buffPos;
      nextPos();
    }
    *s = '\0';
  }
  inline int nextInt() {
    while (!isDig(*buffPos) && *buffPos != '-') {
      nextPos();
    }
    int sign = (*buffPos == '-') ? nextPos(), -1 : 1;
    int res = 0;
    while (isDig(*buffPos)) {
      res = res * 10 + *buffPos - '0';
      nextPos();
    }
    return res * sign;
  }
  inline long long nextLong() {
    while (!isDig(*buffPos) && *buffPos != '-') {
      nextPos();
    }
    long long sign = (*buffPos == '-') ? nextPos(), -1 : 1;
    long long res = 0;
    while (isDig(*buffPos)) {
      res = res * 10 + *buffPos - '0';
      nextPos();
    }
    return res * sign;
  }
  inline int n() {
    while (*buffPos < '0' || *buffPos > '9') {
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    int res = 0;
    while (*buffPos >= '0' && *buffPos <= '9') {
      res = res * 10 + (*buffPos - '0');
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    return res;
  }
  inline long long nl() {
    while (*buffPos < '0' || *buffPos > '9') {
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    long long res = 0;
    while (*buffPos >= '0' && *buffPos <= '9') {
      res = res * 10 + (*buffPos - '0');
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    return res;
  }
  inline long long nlm(const int MOD) {
    while (*buffPos < '0' || *buffPos > '9') {
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    long long res = 0;
    while (*buffPos >= '0' && *buffPos <= '9') {
      res = (res * 10 + (*buffPos - '0')) % MOD;
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    return res;
  }
  inline double nextDouble() {
    while (isWS(*buffPos)) {
      nextPos();
    }
    int sign = (*buffPos == '-') ? nextPos(), -1 : 1;
    double res = 0;
    while (isDig(*buffPos)) {
      res = res * 10 + *buffPos - '0';
      nextPos();
    }
    if (*buffPos == '.') {
      nextPos();
      double ep = 1;
      while (isDig(*buffPos)) {
        ep *= 0.1;
        res += ep * (*buffPos - '0');
        nextPos();
      }
    }
    return sign * res;
  }
  inline char nextChar() {
    while (isWS(*buffPos)) nextPos();
    char res = *buffPos;
    nextPos();
    return res;
  }
  ~Scanner() { fclose(file); }
};
Scanner sc(stdin);
template <class __TyFirst, class __TySecond>
std::ostream& operator<<(std::ostream& out,
                         const std::pair<__TyFirst, __TySecond>& o);
static std::string cout_list_sep = " ";
template <
    class IterateType, typename = decltype(std::declval<IterateType>().begin()),
    typename = decltype(std::declval<IterateType>().end()),
    typename = typename std::enable_if<std::is_convertible<
        typename std::iterator_traits<
            typename IterateType::iterator>::iterator_category,
        std::input_iterator_tag>::value>::type,
    typename = typename std::enable_if<!std::is_base_of<
        std::string, typename std::decay<IterateType>::type>::value>::type,
    typename value_type = typename IterateType::value_type>
std::ostream& operator<<(std::ostream& out, const IterateType& a) {
  for (const auto& i : a) out << i << cout_list_sep;
  return out;
}
template <class __TyFirst, class __TySecond>
std::ostream& operator<<(std::ostream& out,
                         const std::pair<__TyFirst, __TySecond>& o) {
  out << "(" << o.first << "," << o.second << ")";
  return out;
}
template <typename _ForwardIterator>
void logArray(_ForwardIterator, _ForwardIterator, const char* = 0) {}
namespace Temps {
template <typename _IntType>
class RangeInt {
  static_assert(std::is_integral<_IntType>::value,
                "RangeInt object must have integral value type");

 public:
  class iterator : public std::iterator<std::input_iterator_tag, _IntType,
                                        _IntType, const _IntType*, _IntType> {
    _IntType val, step;

   public:
    using typename std::iterator<std::input_iterator_tag, _IntType, _IntType,
                                 const _IntType*, _IntType>::reference;
    explicit constexpr iterator(int val, int step) noexcept
        : val(val), step(step) {}
    constexpr iterator& operator++() noexcept {
      val += step;
      return *this;
    }
    constexpr iterator operator++(int) noexcept {
      iterator ret = *this;
      val += step;
      return ret;
    }
    constexpr bool operator==(const iterator& rhs) const noexcept {
      return val == rhs.val;
    }
    constexpr bool operator!=(const iterator& rhs) const noexcept {
      return val != rhs.val;
    }
    constexpr reference operator*() const { return val; }
  };
  const _IntType _begin, _step, _end;
  explicit constexpr RangeInt(const _IntType end) noexcept
      : _begin(0), _step(1), _end(end > 0 ? end : 0) {}
  explicit constexpr RangeInt(const _IntType begin, const _IntType end) noexcept
      : _begin(begin), _step(1), _end(end > begin ? end : begin) {}
  explicit constexpr RangeInt(const _IntType begin, const _IntType end,
                              const _IntType step)
      : _begin(begin),
        _step(step),
        _end(((step > 0 && end <= begin) || (step < 0 && end >= begin))
                 ? begin
                 : (step > 0
                        ? begin + (end - begin + step - 1) / step * step
                        : begin + (begin - end - step - 1) / (-step) * step)) {}
  constexpr iterator begin() const noexcept { return iterator(_begin, _step); }
  constexpr iterator end() const noexcept { return iterator(_end, _step); }
  constexpr _IntType size() const noexcept { return (_end - _begin) / _step; }
};
template <class IntType, typename = typename std::enable_if<
                             std::is_integral<IntType>::value>::type>
inline constexpr RangeInt<IntType> range(IntType arg1) {
  return RangeInt<IntType>(arg1);
}
template <class IntType, typename = typename std::enable_if<
                             std::is_integral<IntType>::value>::type>
inline constexpr RangeInt<IntType> range(IntType arg1, IntType arg2) {
  return RangeInt<IntType>(arg1, arg2);
}
template <class IntType, typename = typename std::enable_if<
                             std::is_integral<IntType>::value>::type>
inline constexpr RangeInt<IntType> range(IntType arg1, IntType arg2,
                                         IntType arg3) {
  return RangeInt<IntType>(arg1, arg2, arg3);
}
}  // namespace Temps
using Temps::range;
namespace Temps {
template <class T>
inline bool checkMin(T& a, T b) {
  return (b < a ? a = b, 1 : 0);
}
template <class T>
inline bool checkMax(T& a, T b) {
  return (a < b ? a = b, 1 : 0);
}
template <class IntType, typename = typename std::enable_if<
                             std::is_integral<IntType>::value>::type>
IntType gcd(const IntType a, const IntType b) {
  return b == 0 ? a : gcd(b, a % b);
}
template <class ForwardIterator, class OutputIterator>
void dissociate(ForwardIterator __begin, ForwardIterator __end,
                OutputIterator __dest) {
  std::vector<typename std::iterator_traits<ForwardIterator>::_IntType> values(
      __begin, __end);
  std::sort(values.begin(), values.end());
  std::unique(values.begin(), values.end());
  while (__begin != __end) {
    *__dest =
        static_cast<typename std::iterator_traits<OutputIterator>::_IntType>(
            std::distance(
                values.begin(),
                std::lower_bound(values.begin(), values.end(), *__begin)));
    __dest++;
    __begin++;
  }
}
}  // namespace Temps
using Temps::checkMax;
using Temps::checkMin;
namespace Temps {
template <class Type>
class Vector {
  static_assert(std::is_trivial<Type>::value,
                "Temps::Vector can only be used for trival types");

 public:
  typedef Type& reference;
  typedef const Type& const_reference;
  class iterator : public std::iterator<std::random_access_iterator_tag, Type> {
   public:
    friend class Vector;
    using typename std::iterator<std::random_access_iterator_tag,
                                 Type>::difference_type;
    using
        typename std::iterator<std::random_access_iterator_tag, Type>::pointer;
    using typename std::iterator<std::random_access_iterator_tag,
                                 Type>::reference;

   private:
    pointer ptr;
    iterator(pointer ptr) : ptr(ptr) {}

   public:
    bool operator==(const iterator rhs) const { return ptr == rhs.ptr; }
    bool operator!=(const iterator rhs) const { return ptr != rhs.ptr; }
    bool operator<(const iterator rhs) const { return ptr < rhs.ptr; }
    bool operator<=(const iterator rhs) const { return ptr <= rhs.ptr; }
    bool operator>(const iterator rhs) const { return ptr > rhs.ptr; }
    bool operator>=(const iterator rhs) const { return ptr >= rhs.ptr; }
    iterator operator++() { return iterator(++ptr); }
    iterator operator++(int) { return iterator(ptr++); }
    iterator operator--() { return iterator(--ptr); }
    iterator operator--(int) { return iterator(ptr--); }
    iterator operator+(const difference_type dif) const {
      return iterator(ptr + dif);
    }
    iterator operator-(const difference_type dif) const {
      return iterator(ptr - dif);
    }
    iterator operator+=(const difference_type dif) {
      ptr += dif;
      return *this;
    }
    iterator operator-=(const difference_type dif) {
      ptr -= dif;
      return *this;
    }
    difference_type operator-(const iterator& rhs) const {
      return ptr - rhs.ptr;
    }
    operator pointer() { return ptr; }
  };

 protected:
  Type* a = nullptr;
  unsigned int _capacity = 0, _size = 0;
  void __grow_capacity(unsigned int least_size) {
    if (_capacity >= least_size) {
      return;
    }
    if (_capacity == 0) {
      _capacity = 1;
    }
    while (_capacity < least_size) {
      _capacity = _capacity * 2;
    }
    a = static_cast<Type*>(realloc(a, sizeof(Type) * _capacity));
  }

 public:
  Vector() = default;
  explicit Vector(unsigned int size, const Type& initial_value = Type())
      : _capacity(size), _size(size) {
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type *__first = a, *const __last = a + _size;
    while (__first != __last) {
      *__first++ = initial_value;
    }
  }
  Vector(const Vector& rhs) : _capacity(rhs._size), _size(rhs._size) {
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type *__first = a, *__r_p = rhs.a, *const __last = a + _size;
    while (__first != __last) {
      *__first++ = *__r_p++;
    }
  }
  Vector(Vector&& rhs) : _capacity(rhs._capacity), _size(rhs._size) {
    a = rhs.a;
    rhs.a = nullptr;
  }
  Vector(const std::initializer_list<Type>& list)
      : _capacity(
            static_cast<unsigned int>(std::distance(list.begin(), list.end()))),
        _size(_capacity) {
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type* p = a;
    for (const auto& i : list) {
      *p++ = i;
    }
  }
  template <typename Container,
            typename = decltype(std::declval<Container>().begin(),
                                std::declval<Container>().end())>
  Vector(const Container& list)
      : _capacity(
            static_cast<unsigned int>(std::distance(list.begin(), list.end()))),
        _size(_capacity) {
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type* p = a;
    for (const auto& i : list) {
      *p++ = i;
    }
  }
  template <
      typename _InputIterator,
      typename = typename std::enable_if<std::is_convertible<
          typename std::iterator_traits<_InputIterator>::iterator_category,
          std::input_iterator_tag>::value>::type>
  explicit Vector(_InputIterator __first, _InputIterator __last) {
    _size = _capacity =
        static_cast<unsigned int>(std::distance(__first, __last));
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type* p = a;
    while (__first != __last) {
      *p++ = *__first++;
    }
  }
  inline bool empty() const { return _size == 0; }
  inline unsigned int size() const { return _size; }
  inline unsigned int capacity() const { return _capacity; }
  void reserve(unsigned int __capacity) {
    _capacity = __capacity;
    if (_size > _capacity) {
      _size = _capacity;
    }
    a = static_cast<Type*>(realloc(a, sizeof(Type) * _capacity));
  }
  void resize(unsigned int __size) {
    if (_size > __size) {
      _size = __size;
      return;
    }
    __grow_capacity(__size);
    Type *__un = a + _size, *const __ed = a + __size;
    while (__un != __ed) {
      *__un++ = Type();
    }
    _size = __size;
  }
  inline void clear() { resize(0); }
  Vector& operator=(const Vector& rhs) {
    __grow_capacity(rhs._size);
    _size = rhs._size;
    Type* __first = a;
    const Type *const __last = a + _size, *__r_p = rhs.a;
    while (__first != __last) {
      *__first++ = *__r_p++;
    }
    return *this;
  }
  Vector& operator=(Vector&& rhs) {
    _size = rhs._size;
    _capacity = rhs._capacity;
    free(a);
    a = rhs.a;
    rhs.a = nullptr;
    return *this;
  }
  Type operator[](const unsigned int id) const { return a[id]; }
  Type& operator[](const unsigned int id) { return a[id]; }
  Type front() const { return a[0]; }
  Type& front() { return a[0]; }
  Type back() const { return a[_size - 1]; }
  Type& back() { return a[_size - 1]; }
  void pop_back() { _size--; }
  Vector& push_back(const Type& b) {
    __grow_capacity(_size + 1);
    a[_size] = b;
    _size++;
    return *this;
  }
  Vector& push_back(const Vector& rhs) {
    __grow_capacity(_size + rhs._size);
    for (const auto& i : rhs) {
      a[_size++] = i;
    }
    return *this;
  }
  Vector& push_back(const std::initializer_list<Type>& rhs) {
    __grow_capacity(_size + rhs.size());
    for (const auto& i : rhs) {
      a[_size++] = i;
    }
    return *this;
  }
  inline iterator begin() const { return iterator(a); }
  inline iterator end() const { return iterator(a + _size); }
  ~Vector() { free(a); }
};
}  // namespace Temps
using Temps::Vector;
void preInit();
void init();
void solve();
int32_t main() {
  preInit();
  init();
  solve();
  return 0;
}
constexpr long long N = 100005;
struct dp_t {
  long long ss = 0, sub_sr = 0, ss_sr = 0;
  dp_t() = default;
  dp_t(long long val) : ss(val), sub_sr(val), ss_sr(val) {}
};
std::vector<long long> e[N];
long long n, w[N], ans = 0;
void preInit() {}
void init() {
  n = sc.n();
  for (long long i = 1; i <= n; i++) w[i] = sc.n();
  for (long long i = 1; i < n; i++) {
    long long u = sc.n(), v = sc.n();
    e[u].push_back(v);
    e[v].push_back(u);
  }
}
dp_t dp[N];
void dfs(long long u, long long f) {
  dp[u] = dp_t(w[u]);
  long long pre_v_sub_sr = 0;
  for (long long v : e[u])
    if (v != f) {
      dfs(v, u);
      const dp_t& dv = dp[v];
      dp_t du;
      du.ss = std::max(dp[u].ss, w[u] + dv.ss);
      du.sub_sr = std::max({dp[u].sub_sr, dp[u].ss + dv.ss, dv.sub_sr});
      du.ss_sr = std::max({dp[u].ss_sr, dp[u].ss + dv.sub_sr,
                           pre_v_sub_sr + w[u] + dv.ss, dv.ss_sr + w[u]});
      pre_v_sub_sr = std::max(pre_v_sub_sr, dv.sub_sr);
      ans = std::max({ans, dp[u].sub_sr + dv.sub_sr, dp[u].ss_sr + dv.ss,
                      dp[u].ss + dv.ss_sr});
      dp[u] = du;
    }
}
void solve() {
  dfs(1, 0);
  printf("%lld\n", ans);
}

### Prompt

Your task is to create a CPP solution to the following problem:

Alice and Bob have a tree (undirected acyclic connected graph). There are ai chocolates waiting to be picked up in the i-th vertex of the tree. First, they choose two different vertices as their starting positions (Alice chooses first) and take all the chocolates contained in them.

Then, they alternate their moves, selecting one vertex at a time and collecting all chocolates from this node. To make things more interesting, they decided that one can select a vertex only if he/she selected a vertex adjacent to that one at his/her previous turn and this vertex has not been already chosen by any of them during other move.

If at any moment one of them is not able to select the node that satisfy all the rules, he/she will skip his turns and let the other person pick chocolates as long as he/she can. This goes on until both of them cannot pick chocolates any further.

Due to their greed for chocolates, they want to collect as many chocolates as possible. However, as they are friends they only care about the total number of chocolates they obtain together. What is the maximum total number of chocolates they may pick?

Input

The first line of the input contains the single integer n (2 ≤ n ≤ 100 000) — the number of vertices in the tree.

The second line contains n integers ai (1 ≤ ai ≤ 109), i-th of these numbers stands for the number of chocolates stored at the node i.

Then follow n - 1 lines that describe the tree. Each of them contains two integers ui and vi (1 ≤ ui, vi ≤ n) — indices of vertices connected by the i-th edge.

Output

Print the number of chocolates Alice and Bob can collect together if they behave optimally.

Examples

Input

9
1 2 3 4 5 6 7 8 9
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9


Output

25


Input

2
20 10
1 2


Output

30

Note

In the first sample, Alice may start at the vertex 9 and Bob at vertex 8. Alice will select vertex 1 and Bob has no options now. Alice selects the vertex 7 and they both stop.

In the second sample, both of them will pick either of the nodes alternately.

### Response

```cpp
#include <bits/stdc++.h>
class Scanner {
 private:
  static const int BUFFER_SIZE = 1 << 18;
  char buff[BUFFER_SIZE];
  char *buffPos, *buffLim;
  FILE* file;

 public:
  Scanner(FILE* file) {
    this->file = file;
    buffLim = buff + fread(buff, 1, BUFFER_SIZE, file);
    buffPos = buff;
  }

 private:
  inline void flushBuff() {
    buffLim = buff + fread(buff, 1, BUFFER_SIZE, file);
    if (buffLim == buff) {
      *buffLim++ = '\n';
    }
    buffPos = buff;
  }
  inline bool isWS(char t) { return t <= ' '; }
  inline bool isDig(char t) { return t >= '0' && t <= '9'; }
  inline void nextPos() {
    buffPos++;
    if (buffPos == buffLim) {
      flushBuff();
    }
  }

 public:
  inline char getchar() {
    char ch = *buffPos;
    nextPos();
    return ch;
  }
  inline void next(char* s) {
    while (isWS(*buffPos)) {
      nextPos();
    }
    while (!isWS(*buffPos)) {
      *s = *buffPos;
      s++;
      nextPos();
    }
    *s = '\0';
  }
  inline void nextLine(char* s) {
    while (*buffPos != '\n') {
      nextPos();
    }
    if (*buffPos == '\n') {
      nextPos();
    }
    while (*buffPos != '\n') {
      *s++ = *buffPos;
      nextPos();
    }
    *s = '\0';
  }
  inline int nextInt() {
    while (!isDig(*buffPos) && *buffPos != '-') {
      nextPos();
    }
    int sign = (*buffPos == '-') ? nextPos(), -1 : 1;
    int res = 0;
    while (isDig(*buffPos)) {
      res = res * 10 + *buffPos - '0';
      nextPos();
    }
    return res * sign;
  }
  inline long long nextLong() {
    while (!isDig(*buffPos) && *buffPos != '-') {
      nextPos();
    }
    long long sign = (*buffPos == '-') ? nextPos(), -1 : 1;
    long long res = 0;
    while (isDig(*buffPos)) {
      res = res * 10 + *buffPos - '0';
      nextPos();
    }
    return res * sign;
  }
  inline int n() {
    while (*buffPos < '0' || *buffPos > '9') {
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    int res = 0;
    while (*buffPos >= '0' && *buffPos <= '9') {
      res = res * 10 + (*buffPos - '0');
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    return res;
  }
  inline long long nl() {
    while (*buffPos < '0' || *buffPos > '9') {
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    long long res = 0;
    while (*buffPos >= '0' && *buffPos <= '9') {
      res = res * 10 + (*buffPos - '0');
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    return res;
  }
  inline long long nlm(const int MOD) {
    while (*buffPos < '0' || *buffPos > '9') {
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    long long res = 0;
    while (*buffPos >= '0' && *buffPos <= '9') {
      res = (res * 10 + (*buffPos - '0')) % MOD;
      buffPos++;
      if (buffPos == buffLim) {
        flushBuff();
      }
    }
    return res;
  }
  inline double nextDouble() {
    while (isWS(*buffPos)) {
      nextPos();
    }
    int sign = (*buffPos == '-') ? nextPos(), -1 : 1;
    double res = 0;
    while (isDig(*buffPos)) {
      res = res * 10 + *buffPos - '0';
      nextPos();
    }
    if (*buffPos == '.') {
      nextPos();
      double ep = 1;
      while (isDig(*buffPos)) {
        ep *= 0.1;
        res += ep * (*buffPos - '0');
        nextPos();
      }
    }
    return sign * res;
  }
  inline char nextChar() {
    while (isWS(*buffPos)) nextPos();
    char res = *buffPos;
    nextPos();
    return res;
  }
  ~Scanner() { fclose(file); }
};
Scanner sc(stdin);
template <class __TyFirst, class __TySecond>
std::ostream& operator<<(std::ostream& out,
                         const std::pair<__TyFirst, __TySecond>& o);
static std::string cout_list_sep = " ";
template <
    class IterateType, typename = decltype(std::declval<IterateType>().begin()),
    typename = decltype(std::declval<IterateType>().end()),
    typename = typename std::enable_if<std::is_convertible<
        typename std::iterator_traits<
            typename IterateType::iterator>::iterator_category,
        std::input_iterator_tag>::value>::type,
    typename = typename std::enable_if<!std::is_base_of<
        std::string, typename std::decay<IterateType>::type>::value>::type,
    typename value_type = typename IterateType::value_type>
std::ostream& operator<<(std::ostream& out, const IterateType& a) {
  for (const auto& i : a) out << i << cout_list_sep;
  return out;
}
template <class __TyFirst, class __TySecond>
std::ostream& operator<<(std::ostream& out,
                         const std::pair<__TyFirst, __TySecond>& o) {
  out << "(" << o.first << "," << o.second << ")";
  return out;
}
template <typename _ForwardIterator>
void logArray(_ForwardIterator, _ForwardIterator, const char* = 0) {}
namespace Temps {
template <typename _IntType>
class RangeInt {
  static_assert(std::is_integral<_IntType>::value,
                "RangeInt object must have integral value type");

 public:
  class iterator : public std::iterator<std::input_iterator_tag, _IntType,
                                        _IntType, const _IntType*, _IntType> {
    _IntType val, step;

   public:
    using typename std::iterator<std::input_iterator_tag, _IntType, _IntType,
                                 const _IntType*, _IntType>::reference;
    explicit constexpr iterator(int val, int step) noexcept
        : val(val), step(step) {}
    constexpr iterator& operator++() noexcept {
      val += step;
      return *this;
    }
    constexpr iterator operator++(int) noexcept {
      iterator ret = *this;
      val += step;
      return ret;
    }
    constexpr bool operator==(const iterator& rhs) const noexcept {
      return val == rhs.val;
    }
    constexpr bool operator!=(const iterator& rhs) const noexcept {
      return val != rhs.val;
    }
    constexpr reference operator*() const { return val; }
  };
  const _IntType _begin, _step, _end;
  explicit constexpr RangeInt(const _IntType end) noexcept
      : _begin(0), _step(1), _end(end > 0 ? end : 0) {}
  explicit constexpr RangeInt(const _IntType begin, const _IntType end) noexcept
      : _begin(begin), _step(1), _end(end > begin ? end : begin) {}
  explicit constexpr RangeInt(const _IntType begin, const _IntType end,
                              const _IntType step)
      : _begin(begin),
        _step(step),
        _end(((step > 0 && end <= begin) || (step < 0 && end >= begin))
                 ? begin
                 : (step > 0
                        ? begin + (end - begin + step - 1) / step * step
                        : begin + (begin - end - step - 1) / (-step) * step)) {}
  constexpr iterator begin() const noexcept { return iterator(_begin, _step); }
  constexpr iterator end() const noexcept { return iterator(_end, _step); }
  constexpr _IntType size() const noexcept { return (_end - _begin) / _step; }
};
template <class IntType, typename = typename std::enable_if<
                             std::is_integral<IntType>::value>::type>
inline constexpr RangeInt<IntType> range(IntType arg1) {
  return RangeInt<IntType>(arg1);
}
template <class IntType, typename = typename std::enable_if<
                             std::is_integral<IntType>::value>::type>
inline constexpr RangeInt<IntType> range(IntType arg1, IntType arg2) {
  return RangeInt<IntType>(arg1, arg2);
}
template <class IntType, typename = typename std::enable_if<
                             std::is_integral<IntType>::value>::type>
inline constexpr RangeInt<IntType> range(IntType arg1, IntType arg2,
                                         IntType arg3) {
  return RangeInt<IntType>(arg1, arg2, arg3);
}
}  // namespace Temps
using Temps::range;
namespace Temps {
template <class T>
inline bool checkMin(T& a, T b) {
  return (b < a ? a = b, 1 : 0);
}
template <class T>
inline bool checkMax(T& a, T b) {
  return (a < b ? a = b, 1 : 0);
}
template <class IntType, typename = typename std::enable_if<
                             std::is_integral<IntType>::value>::type>
IntType gcd(const IntType a, const IntType b) {
  return b == 0 ? a : gcd(b, a % b);
}
template <class ForwardIterator, class OutputIterator>
void dissociate(ForwardIterator __begin, ForwardIterator __end,
                OutputIterator __dest) {
  std::vector<typename std::iterator_traits<ForwardIterator>::_IntType> values(
      __begin, __end);
  std::sort(values.begin(), values.end());
  std::unique(values.begin(), values.end());
  while (__begin != __end) {
    *__dest =
        static_cast<typename std::iterator_traits<OutputIterator>::_IntType>(
            std::distance(
                values.begin(),
                std::lower_bound(values.begin(), values.end(), *__begin)));
    __dest++;
    __begin++;
  }
}
}  // namespace Temps
using Temps::checkMax;
using Temps::checkMin;
namespace Temps {
template <class Type>
class Vector {
  static_assert(std::is_trivial<Type>::value,
                "Temps::Vector can only be used for trival types");

 public:
  typedef Type& reference;
  typedef const Type& const_reference;
  class iterator : public std::iterator<std::random_access_iterator_tag, Type> {
   public:
    friend class Vector;
    using typename std::iterator<std::random_access_iterator_tag,
                                 Type>::difference_type;
    using
        typename std::iterator<std::random_access_iterator_tag, Type>::pointer;
    using typename std::iterator<std::random_access_iterator_tag,
                                 Type>::reference;

   private:
    pointer ptr;
    iterator(pointer ptr) : ptr(ptr) {}

   public:
    bool operator==(const iterator rhs) const { return ptr == rhs.ptr; }
    bool operator!=(const iterator rhs) const { return ptr != rhs.ptr; }
    bool operator<(const iterator rhs) const { return ptr < rhs.ptr; }
    bool operator<=(const iterator rhs) const { return ptr <= rhs.ptr; }
    bool operator>(const iterator rhs) const { return ptr > rhs.ptr; }
    bool operator>=(const iterator rhs) const { return ptr >= rhs.ptr; }
    iterator operator++() { return iterator(++ptr); }
    iterator operator++(int) { return iterator(ptr++); }
    iterator operator--() { return iterator(--ptr); }
    iterator operator--(int) { return iterator(ptr--); }
    iterator operator+(const difference_type dif) const {
      return iterator(ptr + dif);
    }
    iterator operator-(const difference_type dif) const {
      return iterator(ptr - dif);
    }
    iterator operator+=(const difference_type dif) {
      ptr += dif;
      return *this;
    }
    iterator operator-=(const difference_type dif) {
      ptr -= dif;
      return *this;
    }
    difference_type operator-(const iterator& rhs) const {
      return ptr - rhs.ptr;
    }
    operator pointer() { return ptr; }
  };

 protected:
  Type* a = nullptr;
  unsigned int _capacity = 0, _size = 0;
  void __grow_capacity(unsigned int least_size) {
    if (_capacity >= least_size) {
      return;
    }
    if (_capacity == 0) {
      _capacity = 1;
    }
    while (_capacity < least_size) {
      _capacity = _capacity * 2;
    }
    a = static_cast<Type*>(realloc(a, sizeof(Type) * _capacity));
  }

 public:
  Vector() = default;
  explicit Vector(unsigned int size, const Type& initial_value = Type())
      : _capacity(size), _size(size) {
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type *__first = a, *const __last = a + _size;
    while (__first != __last) {
      *__first++ = initial_value;
    }
  }
  Vector(const Vector& rhs) : _capacity(rhs._size), _size(rhs._size) {
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type *__first = a, *__r_p = rhs.a, *const __last = a + _size;
    while (__first != __last) {
      *__first++ = *__r_p++;
    }
  }
  Vector(Vector&& rhs) : _capacity(rhs._capacity), _size(rhs._size) {
    a = rhs.a;
    rhs.a = nullptr;
  }
  Vector(const std::initializer_list<Type>& list)
      : _capacity(
            static_cast<unsigned int>(std::distance(list.begin(), list.end()))),
        _size(_capacity) {
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type* p = a;
    for (const auto& i : list) {
      *p++ = i;
    }
  }
  template <typename Container,
            typename = decltype(std::declval<Container>().begin(),
                                std::declval<Container>().end())>
  Vector(const Container& list)
      : _capacity(
            static_cast<unsigned int>(std::distance(list.begin(), list.end()))),
        _size(_capacity) {
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type* p = a;
    for (const auto& i : list) {
      *p++ = i;
    }
  }
  template <
      typename _InputIterator,
      typename = typename std::enable_if<std::is_convertible<
          typename std::iterator_traits<_InputIterator>::iterator_category,
          std::input_iterator_tag>::value>::type>
  explicit Vector(_InputIterator __first, _InputIterator __last) {
    _size = _capacity =
        static_cast<unsigned int>(std::distance(__first, __last));
    a = static_cast<Type*>(malloc(sizeof(Type) * _capacity));
    Type* p = a;
    while (__first != __last) {
      *p++ = *__first++;
    }
  }
  inline bool empty() const { return _size == 0; }
  inline unsigned int size() const { return _size; }
  inline unsigned int capacity() const { return _capacity; }
  void reserve(unsigned int __capacity) {
    _capacity = __capacity;
    if (_size > _capacity) {
      _size = _capacity;
    }
    a = static_cast<Type*>(realloc(a, sizeof(Type) * _capacity));
  }
  void resize(unsigned int __size) {
    if (_size > __size) {
      _size = __size;
      return;
    }
    __grow_capacity(__size);
    Type *__un = a + _size, *const __ed = a + __size;
    while (__un != __ed) {
      *__un++ = Type();
    }
    _size = __size;
  }
  inline void clear() { resize(0); }
  Vector& operator=(const Vector& rhs) {
    __grow_capacity(rhs._size);
    _size = rhs._size;
    Type* __first = a;
    const Type *const __last = a + _size, *__r_p = rhs.a;
    while (__first != __last) {
      *__first++ = *__r_p++;
    }
    return *this;
  }
  Vector& operator=(Vector&& rhs) {
    _size = rhs._size;
    _capacity = rhs._capacity;
    free(a);
    a = rhs.a;
    rhs.a = nullptr;
    return *this;
  }
  Type operator[](const unsigned int id) const { return a[id]; }
  Type& operator[](const unsigned int id) { return a[id]; }
  Type front() const { return a[0]; }
  Type& front() { return a[0]; }
  Type back() const { return a[_size - 1]; }
  Type& back() { return a[_size - 1]; }
  void pop_back() { _size--; }
  Vector& push_back(const Type& b) {
    __grow_capacity(_size + 1);
    a[_size] = b;
    _size++;
    return *this;
  }
  Vector& push_back(const Vector& rhs) {
    __grow_capacity(_size + rhs._size);
    for (const auto& i : rhs) {
      a[_size++] = i;
    }
    return *this;
  }
  Vector& push_back(const std::initializer_list<Type>& rhs) {
    __grow_capacity(_size + rhs.size());
    for (const auto& i : rhs) {
      a[_size++] = i;
    }
    return *this;
  }
  inline iterator begin() const { return iterator(a); }
  inline iterator end() const { return iterator(a + _size); }
  ~Vector() { free(a); }
};
}  // namespace Temps
using Temps::Vector;
void preInit();
void init();
void solve();
int32_t main() {
  preInit();
  init();
  solve();
  return 0;
}
constexpr long long N = 100005;
struct dp_t {
  long long ss = 0, sub_sr = 0, ss_sr = 0;
  dp_t() = default;
  dp_t(long long val) : ss(val), sub_sr(val), ss_sr(val) {}
};
std::vector<long long> e[N];
long long n, w[N], ans = 0;
void preInit() {}
void init() {
  n = sc.n();
  for (long long i = 1; i <= n; i++) w[i] = sc.n();
  for (long long i = 1; i < n; i++) {
    long long u = sc.n(), v = sc.n();
    e[u].push_back(v);
    e[v].push_back(u);
  }
}
dp_t dp[N];
void dfs(long long u, long long f) {
  dp[u] = dp_t(w[u]);
  long long pre_v_sub_sr = 0;
  for (long long v : e[u])
    if (v != f) {
      dfs(v, u);
      const dp_t& dv = dp[v];
      dp_t du;
      du.ss = std::max(dp[u].ss, w[u] + dv.ss);
      du.sub_sr = std::max({dp[u].sub_sr, dp[u].ss + dv.ss, dv.sub_sr});
      du.ss_sr = std::max({dp[u].ss_sr, dp[u].ss + dv.sub_sr,
                           pre_v_sub_sr + w[u] + dv.ss, dv.ss_sr + w[u]});
      pre_v_sub_sr = std::max(pre_v_sub_sr, dv.sub_sr);
      ans = std::max({ans, dp[u].sub_sr + dv.sub_sr, dp[u].ss_sr + dv.ss,
                      dp[u].ss + dv.ss_sr});
      dp[u] = du;
    }
}
void solve() {
  dfs(1, 0);
  printf("%lld\n", ans);
}

```