#include <bits/stdc++.h>
using namespace std;
int main() {
  bool used[101] = {};
  int n;
  int a[101] = {};
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  int ans = 0;
  while (1) {
    int numbx = 0;
    bool ff = false;
    for (int i = 0; i < n; i++) {
      if (!used[i] && a[i] >= numbx) {
        used[i] = 1;
        numbx++;
        ff = true;
      }
    }
    if (ff) ans++;
    if (!ff) break;
  }
  cout << ans << "\n";
}
