#include <bits/stdc++.h>
using namespace std;
int n, a[101];
bool vis[101];
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  int sum = 0;
  int t = n;
  int flag = 0;
  while (t) {
    flag = 0;
    for (int i = 0; i < n; i++) {
      if (flag <= a[i] && !vis[i]) {
        vis[i] = 1;
        flag++;
        t--;
      }
    }
    sum++;
  }
  cout << sum << endl;
  return 0;
}
