#include <bits/stdc++.h>
using namespace std;
int n;
int x[105];
int main(void) {
  scanf("%d", &n);
  for (int i = (0); i < (n); ++i) scanf("%d", x + i);
  sort(x, x + n);
  int sol = 0;
  for (int i = (0); i < (n); ++i) {
    if (x[i] == -1) continue;
    ++sol;
    int got = 1;
    for (int j = (i + 1); j < (n); ++j) {
      if (x[j] >= got) {
        x[j] = -1;
        ++got;
      }
    }
  }
  printf("%d\n", sol);
  return 0;
}
