#include <bits/stdc++.h>
using namespace std;
const int N = 4e5 + 10, OO = 1e9, Mod = 1e9 + 7;
int n, a[N];
int idx[N];
int lefts[N], rights[N];
stack<pair<int, int>> st;
void rem() {
  while (st.size()) st.pop();
}
int main() {
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
    idx[a[i]] = i;
  }
  for (int i = 1; i <= n; ++i) {
    while (!st.empty() && a[i] >= st.top().first) {
      st.pop();
    }
    if (st.empty())
      lefts[i] = 0;
    else
      lefts[i] = st.top().second;
    st.push({a[i], i});
  }
  rem();
  for (int i = n; i >= 1; --i) {
    while (!st.empty() && a[i] >= st.top().first) {
      st.pop();
    }
    if (st.empty()) {
      rights[i] = n + 1;
    } else {
      rights[i] = st.top().second;
    }
    st.push({a[i], i});
  }
  rem();
  int ans = 0;
  for (int i = 2; i < n; ++i) {
    int rangeleft = i - lefts[i];
    int rangeright = rights[i] - i;
    if (rangeleft >= rangeright) {
      for (int j = i + 1; j < rights[i]; ++j) {
        int need = a[i] - a[j];
        if (idx[need] > lefts[i] && idx[need] < i) ++ans;
      }
    } else {
      for (int j = i - 1; j > lefts[i]; --j) {
        int need = a[i] - a[j];
        if (idx[need] > i && idx[need] < rights[i]) ++ans;
      }
    }
  }
  cout << ans << endl;
}
