#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int arr[n];
  for (int i = 0; i < n; i++) cin >> arr[i];
  sort(arr, arr + n);
  int howmany = 0;
  bool us[n];
  int piles = 0;
  memset(us, false, sizeof us);
  while (howmany < n) {
    piles++;
    int h = 0;
    for (int i = 0; i < n; i++) {
      if (!us[i]) {
        if (arr[i] >= h) {
          h++;
          howmany++;
          us[i] = true;
        }
      }
    }
  }
  cout << piles;
}
