#include <bits/stdc++.h>
using namespace std;
int b[103];
int w[103] = {0};
int ans = 1;
int bb[103];
int main() {
  int n, i, j;
  cin >> n;
  for (i = 1; i <= n; i++) cin >> b[i];
  for (i = 1; i <= n; i++) bb[i] = -1;
  sort(b + 1, b + 1 + n);
  for (i = 1; i <= n; i++) {
    for (j = 1;; j++) {
      if (b[i] >= bb[j] && b[i] >= w[j]) {
        bb[j] = b[i];
        w[j]++;
        break;
      } else if (j == ans)
        ans++;
    }
  }
  cout << ans << endl;
  return 0;
}
