#include <bits/stdc++.h>
using namespace std;
int a[110];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int ret;
    cin >> ret;
    a[ret]++;
  }
  int res = 0;
  for (;;) {
    int k = -1;
    for (int i = 0; i <= 100; i++)
      if (a[i]) {
        k = i;
        break;
      }
    if (k == -1) break;
    res++;
    for (int i = 0;; i++) {
      while (k <= 100 && (a[k] == 0 || k < i)) k++;
      if (k > 100) break;
      a[k]--;
    }
  }
  cout << res << endl;
  return 0;
}
