#include <bits/stdc++.h>
using namespace std;
int const maxn = (int)1e3 + 11;
int const inf = (1 << 30) - 1;
int n;
int a[maxn];
bool used[maxn];
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  sort(a + 1, a + n + 1);
  int sum = 0;
  int ans = 0;
  for (int j = 0; j < n; j++) {
    sum = 0;
    for (int i = 1; i <= n; i++) {
      if (a[i] >= sum && !used[i]) {
        if (sum == 0) ans++;
        sum++;
        used[i] = true;
      }
    }
  }
  cout << ans << endl;
  return 0;
}
