#include <bits/stdc++.h>
using namespace std;
int a[120], b[120];
int main(void) {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) scanf("%d", &a[i]);
  sort(a, a + n);
  int sum = 0;
  while (1) {
    int st = 0;
    while (st < n && b[st] != 0) ++st;
    if (st >= n) break;
    int d = 0;
    for (int i = st; i < n; ++i) {
      if (b[i] == 0 && a[i] >= d) {
        ++d;
        b[i] = 1;
      }
    }
    ++sum;
  }
  printf("%d\n", sum);
}
