#include <bits/stdc++.h>
using namespace std;
int s[110], v[110];
int main() {
  int n, i, j, ans, sum, p;
  while (cin >> n) {
    for (i = 0; i < n; i++) {
      cin >> s[i];
    }
    sort(s, s + n);
    memset(v, 0, sizeof(v));
    sum = 0;
    ans = 0;
    while (sum < n) {
      ans++;
      p = 0;
      for (i = 0; i < n; i++) {
        if (v[i] == 0 && s[i] >= p) {
          v[i] = 1;
          p++;
          sum++;
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}
