#include <bits/stdc++.h>
using namespace std;
int h[110];
bool vis[110];
int main() {
  int n;
  while (cin >> n) {
    for (int i = 0; i < n; ++i) {
      cin >> h[i];
    }
    sort(h, h + n);
    memset(vis, false, sizeof(vis));
    int num = 0;
    int res = 0;
    while (num < n) {
      int pre = 0;
      for (int i = 0; i < n && num < n; ++i) {
        if (pre <= h[i] && !vis[i]) {
          ++pre;
          vis[i] = true;
          ++num;
        }
      }
      ++res;
    }
    cout << res << endl;
  }
  return 0;
}
