#include <bits/stdc++.h>
using namespace std;
long long n, m, a[2000], s, k, l, i, j, b[2000], p;
int main() {
  cin >> n;
  for (i = 1; i <= n; i++) cin >> a[i];
  sort(a + 1, a + 1 + n);
  while (p == 0) {
    p = 1;
    l = 0;
    for (i = 1; i <= n; i++)
      if (l <= a[i] && b[i] == 0) {
        l++;
        b[i] = 1;
      }
    if (l != 0) {
      k++;
      p = 0;
    }
  }
  cout << k;
  return 0;
}
