#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long int n;
  cin >> n;
  ;
  long long int a[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  long long int dp[n];
  memset(dp, 0, sizeof(dp));
  long long int ans = 0;
  int c1 = 0;
  int f = 0;
  while (f == 0) {
    f = 1;
    for (int i = 0; i < n; i++) {
      if (dp[i] == 0 && a[i] >= c1) {
        dp[i] = 1;
        c1++;
      }
    }
    if (c1 > 0) {
      ans++;
      f = 0;
    }
    c1 = 0;
  }
  cout << ans;
  cout << "\n";
  return 0;
}
