#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n;
  cin >> n;
  vector<long long> a(n);
  for (long long i = 0; i < n; i++) cin >> a[i];
  sort(a.begin(), a.end(), greater<long long>());
  long long low = 1, high = n;
  while (low <= high) {
    long long mid = (low + high) / 2;
    vector<long long> b[mid];
    bool flag = true;
    for (long long j = 0; j < n; j++) {
      b[j % mid].push_back(a[j]);
    }
    for (long long i = 0; i < mid; i++) {
      long long k = b[i].size();
      long long p = k - 1;
      for (long long j = 0; j < k; j++) {
        if (b[i][j] < p) {
          flag = false;
          break;
        }
        p--;
      }
    }
    if (!flag)
      low = mid + 1;
    else
      high = mid - 1;
  }
  cout << low << endl;
}
int main() {
  long long t = 1;
  while (t--) {
    solve();
  }
}
