#include <bits/stdc++.h>
using namespace std;
const int N = 200005;
const int inf = 1000 * 1000 * 1000;
const int mod = 1000 * 1000 * 1000 + 7;
int n;
int a[N];
long long answ = 0;
int mx[N];
bool used[N];
void solve(int s, int e) {
  if (s == e) {
    return;
  }
  int m = (s + e) / 2;
  solve(s, m);
  solve(m + 1, e);
  for (int step = 0; step < 2; step++) {
    for (int i = m + 1; i <= e; i++) {
      mx[i] = (i == m + 1) ? a[i] : max(a[i], mx[i - 1]);
      used[a[i]] = false;
    }
    int it = m + 1, M = 0;
    for (int i = m; i >= s; i--) {
      M = (i == m) ? a[i] : max(M, a[i]);
      while (it <= e && mx[it] < M) {
        used[a[it]] = true;
        ++it;
      }
      int x = M - a[i];
      if (used[x]) {
        ++answ;
      }
    }
    for (int i = m + 1; i <= e; i++) {
      used[a[i]] = false;
    }
    reverse(a + s, a + e + 1);
    m = e - 1 - m + s;
  }
}
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  solve(1, n);
  cout << answ << endl;
  return 0;
}
