#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const long long int LINF = 0x3f3f3f3f3f3f3f3fll;
int main() {
  int n;
  scanf("%d", &n);
  int v[n];
  for (int i = 0; i < n; i++) scanf("%d", &v[i]);
  sort(v, v + n);
  int h[n];
  for (int i = 0; i < n; i++) h[i] = 1;
  int out = 0;
  for (int i = 0; i < n; i++) {
    int x = 0;
    for (int j = 0; j < n; j++) {
      if (h[j] and v[j] >= x) {
        h[j] = 0;
        x++;
      }
    }
    if (x) out++;
  }
  printf("%d\n", out);
  return 0;
}
