#include <bits/stdc++.h>
using namespace std;
const int N = int(2e5) + 9;
int n, k, h;
int need = int(1e9);
int cnt[N];
int main() {
  scanf("%d %d", &n, &k);
  for (int i = 0; i < n; ++i) {
    int x;
    scanf("%d", &x);
    h = max(h, x);
    need = min(need, x);
    ++cnt[x];
  }
  int pos = N - 1;
  int res = 0;
  long long sum = 0;
  int c = 0;
  while (true) {
    long long x = sum - c * 1LL * (pos - 1);
    if (x > k) {
      ++res;
      h = pos;
      sum = pos * 1LL * c;
    }
    --pos;
    if (pos == need) break;
    c += cnt[pos];
    sum += cnt[pos] * 1LL * pos;
  }
  if (h != need) ++res;
  cout << res << endl;
}
