#include <bits/stdc++.h>
int n, size, sol, A[101], obidjen[101];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) scanf("%d", &A[i]);
  std::sort(A + 1, A + n + 1);
  for (int i = 1; i <= n; ++i)
    if (!obidjen[i]) {
      size = 1;
      ++sol;
      obidjen[i] = 1;
      for (int j = i + 1; j <= n; ++j)
        if ((A[j] >= size) && (!obidjen[j])) {
          obidjen[j] = 1;
          ++size;
        }
    }
  printf("%d", sol);
  return 0;
}
