#include <bits/stdc++.h>
using namespace std;
int dx8[] = {0, 0, 1, -1, 1, -1, 1, -1};
int dy8[] = {-1, 1, 0, 0, -1, -1, 1, 1};
int dy[] = {1, -1, 0, 0};
int dx[] = {0, 0, 1, -1};
int X[6] = {0, 0, 0, -1, 0, 1};
int Y[6] = {0, 0, -1, 0, 1, 0};
int Z[6] = {1, -1, 0, 0, 0, 0};
int main() {
  int n;
  scanf("%d", &n);
  vector<int> v(n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &v[i]);
  }
  sort(v.begin(), v.end());
  int ans = 0;
  for (int k = 0; k < n + 10; k++) {
    int stre = 0, what = 0;
    for (int i = 0; i < n; i++) {
      if (v[i] != -1 && !(v[i] < stre)) {
        v[i] = -1;
        what = 1;
        stre++;
      }
    }
    ans += what;
  }
  printf("%d\n", ans);
}
