#include <bits/stdc++.h>
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
int main() {
  long long int n, arr[101];
  scanf("%lld", &n);
  for (int i = 0; i < n; i++) {
    scanf("%lld", &arr[i]);
  }
  long long int count = 0, ans = 0;
  while (count < n) {
    long long int j;
    sort(arr, arr + n);
    for (int i = 0; i < n; i++) {
      if (arr[i] >= 0) {
        j = i;
        break;
      }
    }
    long long int temp = 0;
    while (j < n) {
      if (arr[j] >= temp) {
        arr[j] = -1;
        temp++;
        count++;
      }
      j++;
    }
    ans++;
  }
  printf("%lld\n", ans);
}
