#include <bits/stdc++.h>
using namespace std;
int n, a[101];
bool vis[101];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  sort(a + 1, a + n + 1);
  int ans = 0;
  for (int i = 1; i <= n; i++)
    if (!vis[i]) {
      ans++;
      int now = 1;
      vis[i] = 1;
      for (int j = i + 1; j <= n; j++)
        if (!vis[j]) {
          if (a[j] >= now) {
            vis[j] = 1;
            now++;
          }
        }
    }
  printf("%d\n", ans);
  return 0;
}
