#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 sum = (1 + n) * n / 2;
  int now = 0;
  for (int i = 0; i < n; i++) {
    if (a[i] == 1) {
      now++;
    } else {
      sum -= (now + 1) * now / 2;
      now = 0;
    }
  }
  sum -= (now + 1) * now / 2;
  cout << sum << endl;
  return 0;
}