#include <bits/stdc++.h>
using namespace std;
struct edge {
  long long to, cost;
  edge() {}
  edge(long long a, long long b) { to = a, cost = b; }
};
const long long dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};
const long long mod = 1000000007;
struct mint {
  long long x = 0;
  mint(long long y = 0) {
    x = y;
    if (x < 0 || x >= mod) x = (x % mod + mod) % mod;
  }
  mint(const mint& ope) { x = ope.x; }
  mint operator-() { return mint(-x); }
  mint operator+(const mint& ope) { return mint(x) += ope; }
  mint operator-(const mint& ope) { return mint(x) -= ope; }
  mint operator*(const mint& ope) { return mint(x) *= ope; }
  mint operator/(const mint& ope) { return mint(x) /= ope; }
  mint& operator+=(const mint& ope) {
    x += ope.x;
    if (x >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint& ope) {
    x += mod - ope.x;
    if (x >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint& ope) {
    x *= ope.x, x %= mod;
    return *this;
  }
  mint& operator/=(const mint& ope) {
    long long n = mod - 2;
    mint mul = ope;
    while (n) {
      if (n & 1) *this *= mul;
      mul *= mul;
      n >>= 1;
    }
    return *this;
  }
  mint inverse() { return mint(1) / *this; }
  bool operator==(const mint& ope) { return x == ope.x; }
  bool operator!=(const mint& ope) { return x != ope.x; }
};
mint modpow(mint a, long long n) {
  if (n == 0) return mint(1);
  if (n % 2)
    return a * modpow(a, n - 1);
  else
    return modpow(a * a, n / 2);
}
istream& operator>>(istream& is, mint& ope) {
  long long t;
  is >> t, ope.x = t;
  return is;
}
ostream& operator<<(ostream& os, mint& ope) { return os << ope.x; }
ostream& operator<<(ostream& os, const mint& ope) { return os << ope.x; }
vector<mint> fact, fact_inv;
void make_fact(int n) {
  fact.resize(n + 1), fact_inv.resize(n + 1);
  fact[0] = mint(1);
  for (long long i = (1); (i) <= (n); (i)++) fact[i] = fact[i - 1] * mint(i);
  fact_inv[n] = fact[n].inverse();
  for (long long i = (n - 1); (i) >= (0); (i)--)
    fact_inv[i] = fact_inv[i + 1] * mint(i + 1);
}
mint comb(long long n, long long k) {
  if (n < 0 || k < 0 || n < k) return mint(0);
  return fact[n] * fact_inv[k] * fact_inv[n - k];
}
mint perm(long long n, long long k) { return comb(n, k) * fact[k]; }
vector<int> prime;
void make_prime(int n) {
  prime.resize(n + 1);
  for (long long i = (2); (i) <= (n); (i)++) {
    if (prime[i]) continue;
    for (int j = i; j <= n; j += i) prime[j] = i;
  }
}
bool exceed(long long x, long long y, long long m) { return x >= m / y + 1; }
void mark() { cout << "*" << endl; }
void yes() { cout << "YES" << endl; }
void no() { cout << "NO" << endl; }
long long sgn(long long x) {
  if (x > 0) return 1;
  if (x < 0) return -1;
  return 0;
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long digitnum(long long x, long long b = 10) {
  long long ret = 0;
  for (; x; x /= b) ret++;
  return ret;
}
long long digitsum(long long x, long long b = 10) {
  long long ret = 0;
  for (; x; x /= b) ret += x % b;
  return ret;
}
string lltos(long long x) {
  string ret;
  for (; x; x /= 10) ret += x % 10 + '0';
  reverse(ret.begin(), ret.end());
  return ret;
}
long long stoll(string& s) {
  long long ret = 0;
  for (auto c : s) ret *= 10, ret += c - '0';
  return ret;
}
template <typename T>
void uniq(T& vec) {
  sort(vec.begin(), vec.end());
  vec.erase(unique(vec.begin(), vec.end()), vec.end());
}
template <class S, class T>
pair<S, T>& operator+=(pair<S, T>& s, const pair<S, T>& t) {
  s.first += t.first, s.second += t.second;
  return s;
}
template <class S, class T>
pair<S, T>& operator-=(pair<S, T>& s, const pair<S, T>& t) {
  s.first -= t.first, s.second -= t.second;
  return s;
}
template <class S, class T>
pair<S, T> operator+(const pair<S, T>& s, const pair<S, T>& t) {
  return pair<S, T>(s.first + t.first, s.second + t.second);
}
template <class S, class T>
pair<S, T> operator-(const pair<S, T>& s, const pair<S, T>& t) {
  return pair<S, T>(s.first - t.first, s.second - t.second);
}
template <typename T>
ostream& operator<<(ostream& os, vector<T>& vec) {
  for (int i = 0; i < vec.size(); i++)
    os << vec[i] << (i + 1 == vec.size() ? "" : " ");
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, deque<T>& deq) {
  for (int i = 0; i < deq.size(); i++)
    os << deq[i] << (i + 1 == deq.size() ? "" : " ");
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, pair<T, U>& pair_var) {
  os << "(" << pair_var.first << ", " << pair_var.second << ")";
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& pair_var) {
  os << "(" << pair_var.first << ", " << pair_var.second << ")";
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, map<T, U>& map_var) {
  for (typename map<T, U>::iterator itr = map_var.begin(); itr != map_var.end();
       itr++) {
    os << "(" << itr->first << ", " << itr->second << ")";
    itr++;
    if (itr != map_var.end()) os << ",";
    itr--;
  }
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, set<T>& set_var) {
  for (typename set<T>::iterator itr = set_var.begin(); itr != set_var.end();
       itr++) {
    os << *itr;
    ++itr;
    if (itr != set_var.end()) os << " ";
    itr--;
  }
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, multiset<T>& set_var) {
  for (typename multiset<T>::iterator itr = set_var.begin();
       itr != set_var.end(); itr++) {
    os << *itr;
    ++itr;
    if (itr != set_var.end()) os << " ";
    itr--;
  }
  return os;
}
template <typename T>
void outa(T a[], long long s, long long t) {
  for (long long i = s; i <= t; i++) {
    cout << a[i];
    if (i < t) cout << " ";
  }
  cout << endl;
}
void dump_func() { cout << endl; }
template <class Head, class... Tail>
void dump_func(Head&& head, Tail&&... tail) {
  cout << head;
  if (sizeof...(Tail) > 0) cout << " ";
  dump_func(std::move(tail)...);
}
long long n;
long long h[1000005];
mint dp[1000005];
int main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (long long i = (1); (i) <= (n); (i)++) cin >> h[i];
  if (n == 1) {
    dump_func(h[1] - 1);
    return 0;
  }
  mint ans = mint(0);
  for (long long i = (1); (i) <= (n); (i)++) ans += mint(h[i] - 1);
  dp[1] = min(h[1], h[2]) - 1;
  for (long long i = (2); (i) <= (n - 1); (i)++) {
    dp[i] = dp[i - 1] * mint(min(h[i], min(h[i + 1], h[i - 1])) - 1);
    dp[i] += mint(min(h[i], h[i + 1]) - 1);
  }
  for (long long i = (2); (i) <= (n); (i)++)
    ans += dp[i - 1] * mint(min(h[i - 1], h[i]) - 1);
  dump_func(ans);
  return 0;
}

### Prompt

Create a solution in CPP for the following problem:

Long ago, Vasily built a good fence at his country house. Vasily calls a fence good, if it is a series of n consecutively fastened vertical boards of centimeter width, the height of each in centimeters is a positive integer. The house owner remembers that the height of the i-th board to the left is hi.

Today Vasily decided to change the design of the fence he had built, by cutting his top connected part so that the fence remained good. The cut part should consist of only the upper parts of the boards, while the adjacent parts must be interconnected (share a non-zero length before cutting out of the fence).

You, as Vasily's curious neighbor, will count the number of possible ways to cut exactly one part as is described above. Two ways to cut a part are called distinct, if for the remaining fences there is such i, that the height of the i-th boards vary.

As Vasily's fence can be very high and long, get the remainder after dividing the required number of ways by 1 000 000 007 (109 + 7).

Input

The first line contains integer n (1 ≤ n ≤ 1 000 000) — the number of boards in Vasily's fence.

The second line contains n space-separated numbers h1, h2, ..., hn (1 ≤ hi ≤ 109), where hi equals the height of the i-th board to the left.

Output

Print the remainder after dividing r by 1 000 000 007, where r is the number of ways to cut exactly one connected part so that the part consisted of the upper parts of the boards and the remaining fence was good.

Examples

Input

2
1 1


Output

0


Input

3
3 4 2


Output

13

Note

From the fence from the first example it is impossible to cut exactly one piece so as the remaining fence was good.

All the possible variants of the resulting fence from the second sample look as follows (the grey shows the cut out part): 

<image>

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
struct edge {
  long long to, cost;
  edge() {}
  edge(long long a, long long b) { to = a, cost = b; }
};
const long long dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};
const long long mod = 1000000007;
struct mint {
  long long x = 0;
  mint(long long y = 0) {
    x = y;
    if (x < 0 || x >= mod) x = (x % mod + mod) % mod;
  }
  mint(const mint& ope) { x = ope.x; }
  mint operator-() { return mint(-x); }
  mint operator+(const mint& ope) { return mint(x) += ope; }
  mint operator-(const mint& ope) { return mint(x) -= ope; }
  mint operator*(const mint& ope) { return mint(x) *= ope; }
  mint operator/(const mint& ope) { return mint(x) /= ope; }
  mint& operator+=(const mint& ope) {
    x += ope.x;
    if (x >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint& ope) {
    x += mod - ope.x;
    if (x >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint& ope) {
    x *= ope.x, x %= mod;
    return *this;
  }
  mint& operator/=(const mint& ope) {
    long long n = mod - 2;
    mint mul = ope;
    while (n) {
      if (n & 1) *this *= mul;
      mul *= mul;
      n >>= 1;
    }
    return *this;
  }
  mint inverse() { return mint(1) / *this; }
  bool operator==(const mint& ope) { return x == ope.x; }
  bool operator!=(const mint& ope) { return x != ope.x; }
};
mint modpow(mint a, long long n) {
  if (n == 0) return mint(1);
  if (n % 2)
    return a * modpow(a, n - 1);
  else
    return modpow(a * a, n / 2);
}
istream& operator>>(istream& is, mint& ope) {
  long long t;
  is >> t, ope.x = t;
  return is;
}
ostream& operator<<(ostream& os, mint& ope) { return os << ope.x; }
ostream& operator<<(ostream& os, const mint& ope) { return os << ope.x; }
vector<mint> fact, fact_inv;
void make_fact(int n) {
  fact.resize(n + 1), fact_inv.resize(n + 1);
  fact[0] = mint(1);
  for (long long i = (1); (i) <= (n); (i)++) fact[i] = fact[i - 1] * mint(i);
  fact_inv[n] = fact[n].inverse();
  for (long long i = (n - 1); (i) >= (0); (i)--)
    fact_inv[i] = fact_inv[i + 1] * mint(i + 1);
}
mint comb(long long n, long long k) {
  if (n < 0 || k < 0 || n < k) return mint(0);
  return fact[n] * fact_inv[k] * fact_inv[n - k];
}
mint perm(long long n, long long k) { return comb(n, k) * fact[k]; }
vector<int> prime;
void make_prime(int n) {
  prime.resize(n + 1);
  for (long long i = (2); (i) <= (n); (i)++) {
    if (prime[i]) continue;
    for (int j = i; j <= n; j += i) prime[j] = i;
  }
}
bool exceed(long long x, long long y, long long m) { return x >= m / y + 1; }
void mark() { cout << "*" << endl; }
void yes() { cout << "YES" << endl; }
void no() { cout << "NO" << endl; }
long long sgn(long long x) {
  if (x > 0) return 1;
  if (x < 0) return -1;
  return 0;
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long digitnum(long long x, long long b = 10) {
  long long ret = 0;
  for (; x; x /= b) ret++;
  return ret;
}
long long digitsum(long long x, long long b = 10) {
  long long ret = 0;
  for (; x; x /= b) ret += x % b;
  return ret;
}
string lltos(long long x) {
  string ret;
  for (; x; x /= 10) ret += x % 10 + '0';
  reverse(ret.begin(), ret.end());
  return ret;
}
long long stoll(string& s) {
  long long ret = 0;
  for (auto c : s) ret *= 10, ret += c - '0';
  return ret;
}
template <typename T>
void uniq(T& vec) {
  sort(vec.begin(), vec.end());
  vec.erase(unique(vec.begin(), vec.end()), vec.end());
}
template <class S, class T>
pair<S, T>& operator+=(pair<S, T>& s, const pair<S, T>& t) {
  s.first += t.first, s.second += t.second;
  return s;
}
template <class S, class T>
pair<S, T>& operator-=(pair<S, T>& s, const pair<S, T>& t) {
  s.first -= t.first, s.second -= t.second;
  return s;
}
template <class S, class T>
pair<S, T> operator+(const pair<S, T>& s, const pair<S, T>& t) {
  return pair<S, T>(s.first + t.first, s.second + t.second);
}
template <class S, class T>
pair<S, T> operator-(const pair<S, T>& s, const pair<S, T>& t) {
  return pair<S, T>(s.first - t.first, s.second - t.second);
}
template <typename T>
ostream& operator<<(ostream& os, vector<T>& vec) {
  for (int i = 0; i < vec.size(); i++)
    os << vec[i] << (i + 1 == vec.size() ? "" : " ");
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, deque<T>& deq) {
  for (int i = 0; i < deq.size(); i++)
    os << deq[i] << (i + 1 == deq.size() ? "" : " ");
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, pair<T, U>& pair_var) {
  os << "(" << pair_var.first << ", " << pair_var.second << ")";
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& pair_var) {
  os << "(" << pair_var.first << ", " << pair_var.second << ")";
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, map<T, U>& map_var) {
  for (typename map<T, U>::iterator itr = map_var.begin(); itr != map_var.end();
       itr++) {
    os << "(" << itr->first << ", " << itr->second << ")";
    itr++;
    if (itr != map_var.end()) os << ",";
    itr--;
  }
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, set<T>& set_var) {
  for (typename set<T>::iterator itr = set_var.begin(); itr != set_var.end();
       itr++) {
    os << *itr;
    ++itr;
    if (itr != set_var.end()) os << " ";
    itr--;
  }
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, multiset<T>& set_var) {
  for (typename multiset<T>::iterator itr = set_var.begin();
       itr != set_var.end(); itr++) {
    os << *itr;
    ++itr;
    if (itr != set_var.end()) os << " ";
    itr--;
  }
  return os;
}
template <typename T>
void outa(T a[], long long s, long long t) {
  for (long long i = s; i <= t; i++) {
    cout << a[i];
    if (i < t) cout << " ";
  }
  cout << endl;
}
void dump_func() { cout << endl; }
template <class Head, class... Tail>
void dump_func(Head&& head, Tail&&... tail) {
  cout << head;
  if (sizeof...(Tail) > 0) cout << " ";
  dump_func(std::move(tail)...);
}
long long n;
long long h[1000005];
mint dp[1000005];
int main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (long long i = (1); (i) <= (n); (i)++) cin >> h[i];
  if (n == 1) {
    dump_func(h[1] - 1);
    return 0;
  }
  mint ans = mint(0);
  for (long long i = (1); (i) <= (n); (i)++) ans += mint(h[i] - 1);
  dp[1] = min(h[1], h[2]) - 1;
  for (long long i = (2); (i) <= (n - 1); (i)++) {
    dp[i] = dp[i - 1] * mint(min(h[i], min(h[i + 1], h[i - 1])) - 1);
    dp[i] += mint(min(h[i], h[i + 1]) - 1);
  }
  for (long long i = (2); (i) <= (n); (i)++)
    ans += dp[i - 1] * mint(min(h[i - 1], h[i]) - 1);
  dump_func(ans);
  return 0;
}

```