#include <bits/stdc++.h>
using namespace std;
int a[105];
bool kt[105];
int n, kq;
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  sort(a + 1, a + 1 + n);
  memset(kt, 1, sizeof(kt));
  for (int i = 1; i <= n; i++)
    if (kt[i]) {
      kq++;
      int d = 1;
      int t = a[i];
      int j = i + 1;
      while (j <= n) {
        if (a[j] >= d && kt[j] && a[j] >= t) {
          t = a[j];
          kt[j] = 0;
          d++;
        }
        j++;
      }
    }
  printf("%d", kq);
  return 0;
}
