#include <bits/stdc++.h>
using namespace std;
int main() {
  long n;
  while (cin >> n) {
    long i, ar[2001] = {0}, a, mx = 0, res = 0, f = 0, col[2001] = {0},
            flag = 1;
    for (int i = 0, _n = n; i < _n; i++) cin >> ar[i];
    sort(ar, ar + n);
    while (1) {
      f = 0;
      mx = 0;
      for (int i = 0; i < n; i++) {
        if (col[i]) continue;
        f = 1;
        if (ar[i] >= mx) {
          mx++;
          col[i] = 1;
        }
      }
      if (f) {
        res++;
      } else
        break;
    }
    cout << res << endl;
  }
  return 0;
}
