#include <bits/stdc++.h>
using namespace std;
long long ans;
long long fastPow(long long a, long long b) {
  if (b == 0) {
    return 1;
  }
  ans = fastPow(a, b / 2);
  ans *= ans;
  if (b & 1) {
    return a * ans;
  } else {
    return ans;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, i, j, k, count = 0, sum = 0;
  cin >> n;
  vector<long long> v(n);
  unordered_map<long long, long long> m1;
  for (i = 0; i < n; i++) {
    cin >> v[i];
  }
  sort((v).begin(), (v).end());
  i = 0;
  while (i < n) {
    if (m1[i] == 0) {
      m1[i] = 1;
      count++;
      sum = 1;
      for (j = 0; j < v.size(); j++) {
        if (v[j] >= sum && m1[j] == 0) {
          m1[j] = 1;
          sum++;
        }
      }
    }
    i++;
  }
  cout << count;
}
