#include <bits/stdc++.h>
using namespace std;
const int N = 200;
int a[N];
bool used[N];
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  sort(a, a + n);
  int cnt = 0;
  int ans = 0;
  while (cnt != n) {
    int st = 0;
    for (int i = 0; i < n; i++) {
      if (!used[i]) {
        st = i;
        break;
      }
    }
    int curW = 1;
    used[st] = 1;
    cnt++;
    ans++;
    for (int i = st + 1; i < n; i++) {
      if (!used[i] && a[i] >= curW) {
        used[i] = 1;
        curW++;
        cnt++;
      }
    }
  }
  printf("%d", ans);
  return 0;
}
