#include <bits/stdc++.h>
using namespace std;
template <typename T>
T power(T a, int n, int mod) {
  T res = 1;
  while (n) {
    if (n % 2 == 1) res = (res * a) % mod;
    n /= 2;
    a = (a * a) % mod;
  }
  return res;
}
int maxSeq(vector<int>& v) {
  int lv = v[0];
  int li = 1;
  vector<int> v2;
  for (int i = 1; i < v.size(); i++) {
    if (v[i] >= lv && v[i] - li >= 0) {
      li++;
      lv = v[i];
    } else {
      v2.push_back(v[i]);
    }
  }
  v = v2;
  return 1;
}
int main() {
  int n, a;
  vector<int> v;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a;
    v.push_back(a);
  }
  sort(v.begin(), v.end());
  int ans = 0;
  while (v.size()) {
    ans += maxSeq(v);
  }
  cout << ans;
  return 0;
}
