#include <bits/stdc++.h>
using namespace std;
const int maxn = 111;
int a[maxn];
int b[maxn];
int main() {
  int n;
  while (~scanf("%d", &n)) {
    memset(b, 0, sizeof(b));
    for (int i = 0; i < n; i++) {
      scanf("%d", &a[i]);
      b[a[i]]++;
    }
    sort(a, a + n);
    int x = a[n - 1];
    int t = n;
    int sum = 0;
    int tem = 0;
    while (t) {
      tem = 0;
      for (int i = 0; i <= x; i++) {
        while (b[i] && i >= tem) {
          tem++;
          b[i]--;
          t--;
        }
      }
      sum++;
    }
    printf("%d\n", sum);
  }
  return 0;
}
