#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, j, k, t, Max;
  int a[110], b[110][2];
  while (scanf("%d", &n) != EOF) {
    t = 0;
    for (i = 0; i < n; i++) scanf("%d", &a[i]);
    sort(a, a + n);
    for (i = 0; i < n; i++) b[i][1] = 0, b[i][0] = a[i];
    for (i = 0; i < n; i++) {
      if (b[i][1] == 1) continue;
      Max = 0;
      for (j = i; j < n; j++) {
        if (b[j][1] == 1) continue;
        if (b[j][0] >= Max) {
          b[j][1] = 1;
          Max += 1;
        }
      }
      t += 1;
    }
    printf("%d\n", t);
  }
}
