#include <bits/stdc++.h>
using namespace std;
int M = 1e9 + 7;
void solve() {
  int n;
  cin >> n;
  int a[n];
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (int num = 1; num <= n; num++) {
    int count[num], flag = 0;
    for (int index = 0; index < num; index++) count[index] = 1e9;
    for (int i = n - 1; i >= 0; i--) {
      if (count[i % num] == 0) {
        flag++;
        break;
      }
      count[i % num] = min(count[i % num] - 1, a[i]);
    }
    if (flag == 0) {
      cout << num << "\n";
      return;
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
