#include <bits/stdc++.h>
using namespace std;
int n, x[200], ans, cur;
bool vis[200];
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> x[i];
  sort(x, x + n);
  for (int i = 0; i < n; i++) {
    if (vis[i]) continue;
    ans++;
    for (int j = i + 1; j < n; j++) {
      if (x[j] > cur && !vis[j]) vis[j] = true, cur++;
    }
    cur = 0;
  }
  cout << ans;
  return 0;
}
