#include <bits/stdc++.h>
using namespace std;
int temp = 0, res = 0;
int main() {
  int n;
  int a[102];
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  int h = 0;
  while (temp < n) {
    h = 0;
    res++;
    for (int i = 0; i < n; i++) {
      if (a[i] >= h) {
        a[i] = -100;
        temp++;
        h++;
      }
    }
  }
  cout << res << endl;
  fclose(stdout);
  fclose(stdin);
  return 0;
}
