#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  long n, i, j, x = 0, ans = 0, term = 0;
  long a[101];
  bool vis[101] = {};
  cin >> n;
  for (i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  while (x < n) {
    ans++, term = 0;
    for (i = 0; i < n; i++)
      if (!vis[i] && a[i] >= term) term++, vis[i] = true, x++;
  }
  cout << ans;
  return 0;
}
