#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  int cnt = 1;
  map<int, int> mp;
  for (int i = 0; i < n - 1; i++) {
    if (a[i] - a[i + 1] == -1) {
      cnt++;
    } else {
      mp[cnt]++;
      cnt = 1;
    }
  }
  if (cnt > 1) mp[cnt]++;
  long long ans = 0;
  for (auto i : mp) {
    if (i.first <= 1) continue;
    ans += 1LL * (i.first) * (i.first - 1) / 2 * i.second;
  }
  cout << ans << endl;
  return 0;
}