#include <bits/stdc++.h>
using namespace std;
int n;
int a[200];
bool check(int k) {
  int pos[200];
  for (int i = 0; i < k; i++) pos[i] = 1000000000;
  for (int i = 0; i < n; i++) {
    pos[i % k] = min(pos[i % k] - 1, a[i]);
    if (pos[i % k] < 0) return 0;
  }
  return 1;
}
int search(int s, int f) {
  if (s == f) return s;
  int m = (s + f) / 2;
  if (check(m))
    return search(s, m);
  else
    return search(m + 1, f);
}
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  reverse(a, a + n);
  cout << search(1, n) << endl;
}
