#include <bits/stdc++.h>
using namespace std;
int a[110];
int vis[110];
int n;
int main() {
  int i, j;
  while (scanf("%d", &n) != EOF) {
    memset(vis, 0, sizeof(vis));
    for (i = 1; i <= n; i++) {
      scanf("%d", &a[i]);
    }
    sort(a + 1, a + n + 1);
    int ans = 0;
    int cnt = 0;
    for (i = 1; i <= n; i++) {
      if (vis[i]) continue;
      vis[i] = 1;
      ans++;
      cnt = 1;
      for (j = i + 1; j <= n; j++) {
        if (vis[j]) continue;
        if (a[j] >= cnt) {
          cnt++;
          vis[j] = 1;
        }
      }
    }
    printf("%d\n", ans);
  }
  return 0;
}
