#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, value;
  vector<int> arr, temp;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &value);
    arr.push_back(value);
  }
  int cnt = 1;
  while (true) {
    int prev = 0;
    sort(arr.begin(), arr.end());
    for (int i = 0; i < arr.size(); i++) {
      if (prev > arr[i]) {
        temp.push_back(arr[i]);
      } else {
        prev++;
      }
    }
    if (temp.size() == 0) {
      break;
    }
    cnt++;
    arr = temp;
    temp.clear();
  }
  printf("%d\n", cnt);
  return 0;
}
