#include <bits/stdc++.h>
using namespace std;

int main() {
  int n;
  cin >> n;
  int64_t a[n + 2];
  for (int i = 0; i < n; i++) cin >> a[i];
  a[n] = 0;
  a[n + 1] = 1e9 + 7;
  sort(a, a + n + 2);
  int64_t ans = 0;
  for (int i = 1; i <= n; i++) {
    if (a[i - 1] != a[i] && a[i] != a[i + 1]) ans++;
  }
  cout << ans << endl;
  return 0;
}