#include <bits/stdc++.h>
using namespace std;
int a[101], vis[101] = {0};
int main() {
  ios_base::sync_with_stdio(0);
  ;
  int i, n;
  cin >> n;
  for (i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  int ans = 0, boxes = 0;
  while (boxes < n) {
    ans++;
    int c = 0;
    for (i = 0; i < n; i++) {
      if (a[i] >= c && vis[i] == 0) {
        boxes++;
        c++;
        vis[i] = 1;
      }
    }
  }
  cout << ans;
  return 0;
}
