#include <bits/stdc++.h>
using namespace std;
const int N = 105;
int n, a[N];
bool vis[N];
int main(void) {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &a[i]);
  }
  sort(a, a + n);
  int ans = 0;
  bool flag = true;
  while (flag) {
    ans++;
    int now = 0;
    for (int i = 0; i < n; i++) {
      if (vis[i]) {
        continue;
      }
      if (a[i] >= now) {
        now++;
        vis[i] = true;
      } else {
        continue;
      }
    }
    int t = 0;
    for (int i = 0; i < n; i++) {
      if (!vis[i]) {
        t++;
      }
    }
    if (t == 0) {
      flag = false;
    }
  }
  printf("%d\n", ans);
  return 0;
}
