#include <bits/stdc++.h>
using namespace std;
bool mark[9999];
int main() {
  int n;
  scanf("%d", &n);
  int a[n];
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  sort(a, a + n);
  int count = 0, cnt = 0;
  while (cnt < n) {
    count++;
    int i = 0;
    while (mark[i] && i < n - 1) {
      i++;
    }
    cnt++;
    int f = 1;
    for (int j = i + 1; j < n; j++) {
      if (a[j] >= f && !mark[j]) {
        mark[j] = true;
        cnt++;
        f++;
      }
    }
  }
  cout << count;
}
