#include <bits/stdc++.h>
int bedny[110];
int main() {
  int n;
  scanf("%d", &n);
  int c;
  for (int i = 0; i <= 100; i++) {
    bedny[i] = 0;
  }
  for (int i = 0; i < n; i++) {
    scanf("%d", &c);
    bedny[c]++;
  }
  int p = 0, s = 0;
  for (c = 0; c <= 100; c++) {
    s += p - bedny[c];
    if (s < 0) {
      int t = (-s + c) / (c + 1);
      p += t;
      s += t * (c + 1);
    }
  }
  printf("%d", p);
}
