#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, sum, ans = 0;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int a;
    cin >> a;
    sum += a;
    if (sum == 0) ans += 1;
  }
  cout << ans << endl;
}
