There is a toy building consisting of n towers. Each tower consists of several cubes standing on each other. The i-th tower consists of h_i cubes, so it has height h_i.

Let's define operation slice on some height H as following: for each tower i, if its height is greater than H, then remove some top cubes to make tower's height equal to H. Cost of one "slice" equals to the total number of removed cubes from all towers.

Let's name slice as good one if its cost is lower or equal to k (k ≥ n).

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Calculate the minimum number of good slices you have to do to make all towers have the same height. Of course, it is always possible to make it so.

Input

The first line contains two integers n and k (1 ≤ n ≤ 2 ⋅ 10^5, n ≤ k ≤ 10^9) — the number of towers and the restriction on slices, respectively.

The second line contains n space separated integers h_1, h_2, ..., h_n (1 ≤ h_i ≤ 2 ⋅ 10^5) — the initial heights of towers.

Output

Print one integer — the minimum number of good slices you have to do to make all towers have the same heigth.

Examples

Input

5 5
3 1 2 2 4


Output

2


Input

4 5
2 3 4 5


Output

2

Note

In the first example it's optimal to make 2 slices. The first slice is on height 2 (its cost is 3), and the second one is on height 1 (its cost is 4).
#include <bits/stdc++.h>
using namespace std;
int a[200005];
const int inf = 0x3f3f3f3f;
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  int mn = inf;
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
    mn = min(mn, a[i]);
  }
  for (int i = 1; i <= n; i++) {
    a[i] -= mn;
  }
  sort(a + 1, a + n + 1, greater<int>());
  long long te = 0;
  if (a[1]) te = 1;
  int ans = 0;
  int i;
  for (i = 2; i <= n; i++) {
    if (a[i] == 0) break;
    if (a[i] == a[i - 1]) {
      te++;
      if (te > m) {
        ans++;
        te = i;
      }
    } else {
      int k = a[i - 1] - a[i] - 1;
      if (te == m) {
        ans++;
        te = 0;
      }
      while (k--) {
        te += i - 1;
        if (te > m) {
          ans++;
          te = i - 1;
        } else if (te == m) {
          ans++;
          te = 0;
        }
      }
      te += i;
      if (te > m)
        ans++, te = i;
      else if (te == m)
        ans++, te = 0;
    }
  }
  if (te == m) ans++, te = 0;
  int k = a[i - 1] - a[i] - 1;
  while (k > 0) {
    k--;
    te += i - 1;
    if (te > m)
      ans++, te = i;
    else if (te == m)
      ans++, te = 0;
  }
  if (te) ans++;
  printf("%d\n", ans);
}
