#include <bits/stdc++.h>
using namespace std;
int a[41111], n, was[41111], cnt;
int main(void) {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  int ans = 0;
  while (cnt < n) {
    int x = 0;
    for (int i = 0; i < n; i++)
      if (was[i] == 0 && x <= a[i]) x++, was[i] = 1;
    cnt += x, ans++;
  }
  cout << ans << endl;
  return 0;
}
