#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ul;
typedef signed long long ll;

int main(void)
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  std::cout << std::fixed;
  ll n;
  cin >> n;
  ll a[n+2];
  for (ll i = 0; i < n; ++i) cin >> a[i];
  a[n] = 0; a[n+1] = 1000000007;
  sort(a, a+n+2);
  ll 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;
}