#include <bits/stdc++.h>
using namespace std;
int cnt[1000];
void solve() {
  int n;
  cin >> n;
  vector<int> arr(n);
  for (auto &x : arr) cin >> x;
  sort(arr.begin(), arr.end());
  for (int i = 0; i < n; i++) {
    if (arr[i] != 0) {
      bool flag = false;
      for (int j = arr[i] - 1; j >= 0; j--) {
        if (cnt[j] > 0) {
          cnt[j]--;
          cnt[j + 1]++;
          flag = true;
          break;
        }
      }
      if (!flag) cnt[0]++;
    } else
      cnt[0]++;
  }
  long long int sum = 0;
  for (int i = 0; i < 1000; i++) sum += cnt[i];
  cout << sum;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int t = 1;
  while (t--) solve();
}
