You are given n segments on the Ox-axis. You can drive a nail in any integer point on the Ox-axis line nail so, that all segments containing this point, are considered nailed down. If the nail passes through endpoint of some segment, this segment is considered to be nailed too. What is the smallest number of nails needed to nail all the segments down?

Input

The first line of the input contains single integer number n (1 ≤ n ≤ 1000) — amount of segments. Following n lines contain descriptions of the segments. Each description is a pair of integer numbers — endpoints coordinates. All the coordinates don't exceed 10000 by absolute value. Segments can degenarate to points.

Output

The first line should contain one integer number — the smallest number of nails needed to nail all the segments down. The second line should contain coordinates of driven nails separated by space in any order. If the answer is not unique, output any.

Examples

Input

2
0 2
2 5


Output

1
2 

Input

5
0 3
4 2
4 8
8 10
7 7


Output

3
7 10 3
#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:66777216")
#pragma warning(disable : 4996)
#pragma hdrstop
template <bool... Bools>
struct Disjunction : std::false_type {};
template <bool First, bool... Others>
struct Disjunction<First, Others...>
    : std::integral_constant<bool, First || Disjunction<Others...>::value> {};
template <typename T>
constexpr auto has_begin(int) -> decltype(std::begin(std::declval<T>()), true) {
  return true;
}
template <typename T>
constexpr bool has_begin(...) {
  return false;
}
template <typename T>
using is_container = std::integral_constant<bool, has_begin<T>(0)>;
template <typename T, typename... Types>
using is_one_of = Disjunction<std::is_same<T, Types>::value...>;
template <typename T>
using is_sane_integer = std::integral_constant<
    bool,
    std::is_integral<T>::value &&
        !is_one_of<typename std::remove_cv<T>::type, char, signed char,
                   unsigned char, bool, char16_t, char32_t, wchar_t>::value>;
std::string to_string(const std::string& s) { return '"' + s + '"'; }
std::string to_string(const char* s) { return to_string(std::string(s)); }
std::string to_string(const char ch) { return {'\'', ch, '\''}; }
std::string to_string(const bool b) { return (b ? "true" : "false"); }
template <typename T,
          typename std::enable_if<Disjunction<
              is_sane_integer<T>::value,
              std::is_floating_point<T>::value>::value>::type* = nullptr>
std::string to_string(const T value) {
  return std::to_string(value);
}
template <typename A, typename B>
std::string to_string(const std::pair<A, B>&);
template <typename T,
          typename std::enable_if<is_container<T>::value>::type* = nullptr>
std::string to_string(const T& container) {
  bool is_first = true;
  std::string res = "{";
  for (const auto& x : container) {
    if (!is_first) {
      res += ", ";
    }
    is_first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
template <typename A, typename B>
std::string to_string(const std::pair<A, B>& p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
std::vector<std::string> vec_splitter(std::string s) {
  s += ',';
  std::vector<std::string> res;
  while (!s.empty()) {
    const size_t pos = s.find(',');
    res.emplace_back(s.substr(0, pos));
    s = s.substr(pos + 1);
  }
  return res;
}
void debug_out(std::vector<std::string> __attribute__((unused)) args,
               __attribute__((unused)) int idx,
               __attribute__((unused)) int LINE_NUM) {
  std::cerr << std::endl;
}
template <typename Head, typename... Tail>
void debug_out(std::vector<std::string> args, int idx, int LINE_NUM, Head H,
               Tail... T) {
  std::stringstream ss;
  ss << to_string(H);
  if (idx > 0) {
    std::cerr << ", ";
  } else {
    std::cerr << "Line(" << LINE_NUM << ") ";
  }
  const std::string& arg = args[idx];
  const std::string value = ss.str();
  if (arg == value) {
    std::cerr << arg;
  } else {
    std::cerr << arg << " = " << value;
  }
  debug_out(args, idx + 1, LINE_NUM, T...);
}
namespace std {
template <typename T>
std::istream& operator>>(std::istream& in, std::vector<T>& vec) {
  for (auto& it : vec) {
    in >> it;
  }
  return in;
}
template <typename T, typename U>
std::istream& operator>>(std::istream& in, std::pair<T, U>& rhs) {
  in >> rhs.first >> rhs.second;
  return in;
}
}  // namespace std
void assign_files_input_txt() {
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
}
template <typename T>
class IntegerIterator
    : public std::iterator<std::input_iterator_tag, T, std::ptrdiff_t, T*, T> {
 public:
  using value_type = T;
  constexpr explicit IntegerIterator(const value_type value) : value_(value) {}
  IntegerIterator& operator++() {
    ++value_;
    return *this;
  }
  IntegerIterator operator++(int) {
    IntegerIterator copy = *this;
    ++value_;
    return copy;
  }
  IntegerIterator& operator--() {
    --value_;
    return *this;
  }
  IntegerIterator operator--(int) {
    IntegerIterator copy = *this;
    --value_;
    return copy;
  }
  constexpr value_type operator*() const { return value_; }
  constexpr bool operator==(const IntegerIterator rhs) const {
    return value_ == rhs.value_;
  }
  constexpr bool operator!=(const IntegerIterator rhs) const {
    return !(*this == rhs);
  }
  constexpr value_type operator+(const IntegerIterator rhs) const {
    return value_ + rhs.value_;
  }
  IntegerIterator& operator+=(const IntegerIterator rhs) const {
    value_ += rhs.value_;
    return *this;
  }
  constexpr value_type operator-(const IntegerIterator rhs) const {
    return value_ - rhs.value_;
  }
  IntegerIterator& operator-=(const IntegerIterator rhs) const {
    value_ -= rhs.value_;
    return *this;
  }

 private:
  value_type value_;
};
template <typename T>
class IntegerRange {
 public:
  using const_iterator = IntegerIterator<T>;
  constexpr IntegerRange(const T begin, const T end)
      : begin_(begin), end_(end) {}
  constexpr const_iterator begin() const { return const_iterator(begin_); }
  constexpr const_iterator end() const { return const_iterator(end_); }
  constexpr T size() const { return end_ - begin_; }

 private:
  T begin_;
  T end_;
};
template <typename T>
class ReversedRange {
 public:
  using const_iterator = typename std::decay<T>::type::const_iterator;
  using reverse_iterator = std::reverse_iterator<const_iterator>;
  explicit constexpr ReversedRange(const T& iterable)
      : begin_(iterable.begin()), end_(iterable.end()) {}
  constexpr reverse_iterator begin() const { return reverse_iterator(end_); }
  constexpr reverse_iterator end() const { return reverse_iterator(begin_); }

 private:
  const_iterator begin_;
  const_iterator end_;
};
template <typename T>
ReversedRange<T> reversed(T&& iterable) {
  return ReversedRange<T>{iterable};
}
template <typename T>
constexpr IntegerRange<T> range(const T to) {
  return IntegerRange<T>(0, to);
}
template <typename T>
constexpr IntegerRange<T> range(const T from, const T to) {
  return IntegerRange<T>(from, to);
}
template <typename T>
constexpr IntegerRange<T> inclusiveRange(const T to) {
  return IntegerRange<T>(0, to + 1);
}
template <typename T>
constexpr IntegerRange<T> inclusiveRange(const T from, const T to) {
  return IntegerRange<T>(from, to + 1);
}
template <typename T>
constexpr ReversedRange<IntegerRange<T>> downrange(const T from) {
  return reversed(range(from));
}
template <typename T>
constexpr ReversedRange<IntegerRange<T>> downrange(const T from, const T to) {
  return reversed(range(to, from));
}
template <typename T>
constexpr ReversedRange<IntegerRange<T>> inclusiveDownrange(const T from) {
  return reversed(range(from + 1));
}
template <typename T>
constexpr ReversedRange<IntegerRange<T>> inclusiveDownrange(const T from,
                                                            const T to) {
  return reversed(range(to, from + 1));
}
template <typename R>
void sort(R& range) {
  std::sort(range.begin(), range.end());
}
template <typename R, typename Comp>
void sort(R& range, Comp comp) {
  std::sort(range.begin(), range.end(), comp);
}
template <typename R>
void reverse(R& range) {
  std::reverse(range.begin(), range.end());
}
template <typename R, typename T>
auto lower_bound(const R& range, const T& value) -> decltype(range.begin()) {
  return std::lower_bound(range.begin(), range.end(), value);
}
template <typename R, typename T, typename Comp>
auto lower_bound(const R& range, const T& value, Comp comp)
    -> decltype(range.begin()) {
  return std::lower_bound(range.begin(), range.end(), value, comp);
}
template <typename R, typename T>
auto upper_bound(const R& range, const T& value) -> decltype(range.begin()) {
  return std::upper_bound(range.begin(), range.end(), value);
}
template <typename R, typename T, typename Comp>
auto upper_bound(const R& range, const T& value, Comp comp)
    -> decltype(range.begin()) {
  return std::upper_bound(range.begin(), range.end(), value, comp);
}
template <typename R>
auto min_element(const R& range) -> decltype(range.begin()) {
  return std::min_element(range.begin(), range.end());
}
template <typename R>
auto max_element(const R& range) -> decltype(range.begin()) {
  return std::max_element(range.begin(), range.end());
}
template <typename R>
bool next_permutation(R& range) {
  return std::next_permutation(range.begin(), range.end());
}
template <typename T>
void unique(std::vector<T>& range) {
  range.erase(std::unique(range.begin(), range.end()), range.end());
}
template <typename T>
void dedup(std::vector<T>& range) {
  sort(range);
  unique(range);
}
template <typename R>
R sorted(R range) {
  sort(range);
  return range;
}
template <typename R, typename Comp>
R sorted(R range, Comp comp) {
  sort(range, comp);
  return range;
}
static constexpr long double PI = 3.14159265358979323846;
static constexpr long double EPS = 1e-9;
static constexpr int32_t INF = 0x3f3f3f3f;
static constexpr int64_t LINF = 0x3f3f3f3f3f3f3f3fLL;
static constexpr int32_t DX[8] = {-1, 0, 1, 0, -1, -1, 1, 1};
static constexpr int32_t DY[8] = {0, 1, 0, -1, -1, 1, 1, -1};
static constexpr uint32_t kDayMonth[12] = {31, 28, 31, 30, 31, 30,
                                           31, 31, 30, 31, 30, 31};
enum Direction : uint8_t {
  Up,
  Right,
  Down,
  Left,
  UpLeft,
  UpRight,
  DownRight,
  DownLeft,
  North = Up,
  East = Right,
  South = Down,
  West = Left,
  NorthWest = UpLeft,
  NorthEast = UpRight,
  SouthEast = DownRight,
  SouthWest = DownLeft,
  Unknown = 255
};
namespace Random {
inline std::chrono::system_clock::rep current_timestamp() {
  return std::chrono::system_clock::now().time_since_epoch().count();
}
inline uint64_t get_new_rand_seed() {
  return static_cast<uint64_t>(current_timestamp());
}
inline uint64_t get_rand_seed() {
  static const uint64_t kRandSeed = get_new_rand_seed();
  return kRandSeed;
}
using Engine = std::mt19937_64;
template <typename T>
using Distribution = std::uniform_int_distribution<T>;
inline Engine& random_engine() {
  static Engine engine(get_rand_seed());
  return engine;
}
template <typename T>
inline T get(const T to) {
  Distribution<T> distribution(0, to);
  return distribution(random_engine());
}
template <typename T>
inline T get(const T from, const T to) {
  return get(to - from) + from;
}
template <typename T = int32_t>
inline T get() {
  return get(static_cast<T>(0), std::numeric_limits<T>::max());
}
}  // namespace Random
template <typename T,
          typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
class SafeIntegralHash {
 public:
  const T kRandomValue = static_cast<T>(Random::current_timestamp());
  T operator()(const T& value) const { return value ^ kRandomValue; }
};
template <typename Key, typename Value,
          typename std::enable_if<std::is_integral<Key>::value>::type* =
              nullptr>
using SafeUnorderedMap = std::unordered_map<Key, Value, SafeIntegralHash<Key>>;
template <typename Key, typename Value,
          typename std::enable_if<std::is_integral<Key>::value>::type* =
              nullptr>
using SafeUnorderedMultiMap =
    std::unordered_multimap<Key, Value, SafeIntegralHash<Key>>;
template <typename Key,
          typename std::enable_if<std::is_integral<Key>::value>::type* =
              nullptr>
using SafeUnorderedSet = std::unordered_set<Key, SafeIntegralHash<Key>>;
template <typename Key,
          typename std::enable_if<std::is_integral<Key>::value>::type* =
              nullptr>
using SafeUnorderedMultiSet =
    std::unordered_multiset<Key, SafeIntegralHash<Key>>;
namespace std {
template <typename T, typename U>
struct hash<std::pair<T, U>> {
  std::size_t operator()(const std::pair<T, U>& pair) const {
    return pair.first * 877117 + pair.second;
  }
};
}  // namespace std
template <typename T, typename std::enable_if<
                          std::is_floating_point<T>::value>::type* = nullptr>
inline bool is_equal_to_zero(const T& a) {
  return abs(a) < EPS;
}
template <typename T, typename std::enable_if<
                          !std::is_floating_point<T>::value>::type* = nullptr>
inline bool is_equal_to_zero(const T& a) {
  return a == 0;
}
template <typename T>
inline bool umin(T& a, const T& b) {
  return (b < a ? a = b, true : false);
}
template <typename T>
inline bool umax(T& a, const T& b) {
  return (a < b ? a = b, true : false);
}
template <typename T, size_t N>
struct MakeVector {
  template <typename... Args,
            typename R = std::vector<decltype(MakeVector<T, N - 1>::make_vector(
                std::declval<Args>()...))>>
  static R make_vector(size_t first, Args... sizes) {
    auto inner = MakeVector<T, N - 1>::make_vector(sizes...);
    return R(first, inner);
  }
};
template <typename T>
struct MakeVector<T, 1> {
  template <typename R = std::vector<T>>
  static R make_vector(std::size_t size, const T& value) {
    return R(size, value);
  }
};
template <typename T, typename... Args>
auto make_vector(Args... args)
    -> decltype(MakeVector<T, sizeof...(Args) - 1>::make_vector(args...)) {
  return MakeVector<T, sizeof...(Args) - 1>::make_vector(args...);
}
template <typename T>
inline bool is_leap_year(const T year) {
  return year % 400 == 0 || (year % 100 != 0 && (year & 3) == 0);
}
inline size_t get_days_in_month(const size_t month, const size_t year) {
  return kDayMonth[month] + (month == 1 && is_leap_year(year) ? 1 : 0);
}
using ll = int64_t;
using ull = uint64_t;
using uint = uint32_t;
using ld = long double;
using pii = std::pair<int, int>;
using pll = std::pair<ll, ll>;
using pli = std::pair<ll, int>;
using vi = std::vector<int>;
using vvi = std::vector<vi>;
using vp = std::vector<pii>;
class DOtrezki {
 public:
  static constexpr bool kWriteCaseNumber = false;
  static constexpr bool kMultiTest = false;
  struct Event {
    int x;
    bool close;
    int id;
    std::tuple<int, int, int> as_tuple() const {
      return std::make_tuple(x, close, id);
    }
    bool operator<(const Event& rhs) const {
      return as_tuple() < rhs.as_tuple();
    }
  };
  void solve(std::istream& in, std::ostream& out) {
    int n;
    in >> n;
    std::vector<Event> events;
    for (int i : range(n)) {
      int l, r;
      in >> l >> r;
      if (l > r) {
        std::swap(l, r);
      }
      events.emplace_back(Event{l, false, i});
      events.emplace_back(Event{r, true, i});
    }
    sort(events);
    std::set<int> active;
    std::set<int> used;
    std::vector<int> ans;
    for (const auto& event : events) {
      if (!event.close) {
        active.emplace(event.id);
        continue;
      }
      if (!used.count(event.id)) {
        ans.emplace_back(event.x);
        while (!active.empty()) {
          used.emplace(*active.begin());
          active.erase(active.begin());
        }
      }
    }
    out << ans.size() << std::endl;
    for (int x : ans) {
      out << x << " ";
    }
    out << std::endl;
  }
  DOtrezki() {}
  static constexpr bool kUseCustomChecker = false;
  bool check(std::istringstream in, std::istringstream jury,
             std::istringstream out) {
    return true;
  }
  static constexpr size_t kGeneratedTestsCount = 0;
  static constexpr bool kStopAfterFirstFail = false;
  static void generate_test(std::ostream& test) {}
};
int main() {
  DOtrezki solver;
  std::istream& in(std::cin);
  std::ostream& out(std::cout);
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(nullptr);
  srand(time(nullptr));
  out << std::fixed << std::setprecision(16);
  if (DOtrezki::kMultiTest) {
    size_t tests_count;
    in >> tests_count;
    for (size_t test_id : inclusiveRange<size_t>(1, tests_count)) {
      if (DOtrezki::kWriteCaseNumber) {
        out << "Case #" << test_id << ": ";
      }
      solver.solve(in, out);
    }
  } else {
    solver.solve(in, out);
  }
  return 0;
}
