#include <bits/stdc++.h>
using namespace std;
long long n;
vector<long long> v;
vector<long long> v1;
int main() {
  cin >> n;
  int i, p;
  for (i = 1; i <= n; i++) {
    cin >> p;
    v.push_back(p);
  }
  long long counter = 0;
  while (1) {
    long long sum = 0;
    sort(v.begin(), v.end());
    for (i = 0; i < v.size(); i++) {
      if (i == 0) {
        v[i] = -1;
        sum = sum + 1;
      } else {
        if (v[i] >= sum) {
          v[i] = -1;
          sum++;
        }
      }
    }
    for (i = 0; i < v.size(); i++) {
      if (v[i] == -1)
        continue;
      else
        v1.push_back(v[i]);
    }
    if (v1.empty())
      break;
    else {
      counter++;
      v = v1;
      v1.clear();
    }
  }
  cout << counter + 1 << "\n";
}
