#include <bits/stdc++.h>
using namespace std;
const long long BIGER = 1000000000000000;
const int BIG = 1000000000;
int n;
int a[101];
int f[101];
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  sort(a + 1, a + n + 1);
  int s = 0;
  int g = 0;
  int t = 0;
  while (s < n) {
    t = 0;
    for (int i = 1; i <= n; i++) {
      if (a[i] >= t && f[i] == 0) {
        f[i] = 1;
        t++;
        s++;
      }
    }
    g++;
  }
  cout << g;
  return 0;
}
