#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  int a[n];
  int i;
  for (i = 0; i <= n - 1; i++) scanf("%d", &a[i]);
  sort(a, a + n);
  int ans = 1;
  int vis[110] = {0};
  int j = 0;
  while (1) {
    int c = 0;
    int f = 0;
    for (int k = 0; k < n; k++) {
      f = f + vis[k];
    }
    if (f == n) break;
    for (int i = 0; i < n; i++) {
      if (!vis[i]) {
        if (c <= a[i]) {
          vis[i] = 1;
          c++;
        }
      }
    }
    ans++;
  }
  cout << ans - 1;
  return 0;
}
