#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, ans = 0, c = 0;
  int a[123];
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (int i = 0; i < n; i++) {
    if (a[i] != -1) {
      a[i] = -1;
      c++;
      for (int j = i + 1; j < n; j++) {
        if (a[j] >= c) {
          c++;
          a[j] = -1;
        } else if (a[j] > c) {
          j = i;
          c++;
        }
      }
      ans++;
    }
    c = 0;
  }
  cout << ans;
  return 0;
}
