#include <bits/stdc++.h>
using namespace std;
int a, c[10000], l, mn, p;
bool us[10000];
int main() {
  cin >> a;
  for (int i = 0; i < a; i++) {
    cin >> c[i];
  }
  sort(c, c + a);
  while (a - l) {
    p++;
    int k = 0;
    for (int i = 0; i < a; i++) {
      if (!us[i] && k <= c[i]) {
        k++;
        l++;
        us[i] = 1;
      }
    }
  }
  cout << p;
}
