#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, b = 0, i, j;
  cin >> n;
  vector<int> a(n), d(n + 1);
  for (i = 0; i < n; ++i) {
    cin >> a[i];
    d[a[i]] = i;
  }
  set<int> s = {-1, n};
  for (i = n; i >= 1; --i) {
    auto t = s.upper_bound(d[i]);
    int r = (*t) - 1, l = *(--t) + 1;
    s.insert(d[i]);
    if (d[i] - l < r - d[i])
      for (j = l; j < d[i]; ++j)
        b += (d[i - a[j]] > d[i]) && (d[i - a[j]] <= r);
    else
      for (j = d[i] + 1; j <= r; ++j)
        b += (d[i - a[j]] >= l) && (d[i - a[j]] < d[i]);
  }
  cout << b;
}
