#include <bits/stdc++.h>
using namespace std;
int n;
int a[110];
int num[110];
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    int x;
    scanf("%d", &x);
    num[x]++;
  }
  int ans = 0;
  while (n) {
    int weight = 0;
    for (int i = 0; i <= 100; ++i) {
      while (num[i] && i >= weight) {
        weight++;
        num[i]--;
        n--;
      }
    }
    ans++;
  }
  printf("%d", ans);
}
