#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const double PI = acos(-1.0);
const int MAXN = 2e5 + 5;
long long int freq[MAXN];
long long int pref_sum(int l, int r) {
  return (l ? freq[r] - freq[l - 1] : freq[r]);
}
void cp() {
  int n;
  long long int k;
  cin >> n >> k;
  vector<long long int> arr(n);
  memset(freq, 0, sizeof(freq));
  for (int i = 0; i < n; i++) cin >> arr[i], freq[arr[i]]++;
  for (int i = 1; i < MAXN; i++) freq[i] += freq[i - 1];
  sort(arr.begin(), arr.end());
  int need = arr[0];
  int ans = 0;
  long long int cost = 0;
  for (int i = 2e5; i >= need; i--) {
    long long int cnt = pref_sum(i + 1, MAXN - 1);
    long long int total = cost + cnt;
    if (total > k) {
      ans++;
      cost = cnt;
    } else
      cost += cnt;
  }
  if (cost) {
    ans++;
  }
  cout << ans << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int t;
  t = 1;
  while (t--) {
    cp();
  }
  return 0;
}
