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).
//package main;

import java.io.*;
import java.util.*;
import java.math.*;

public final class Main {
    BufferedReader br;
    StringTokenizer stk;
    
    public static void main(String[] args) throws Exception {
        new Main().run();
    }
    
    {
        stk = null;
        br = new BufferedReader(new InputStreamReader(System.in));
    }
    
    boolean tests = false;
    
    long mod = 1000_000_000 + 7;
    StringBuilder res = new StringBuilder(1000005);
    
    void run() throws Exception {
        int t = tests ? ni() : 1;
        for(int i = 1; i <= t; i++) {
            go(i);
        }
        System.out.print(res.length() == 0 ? "" : res);
    }
    
    void go(int T) throws Exception {
        int SIZE = 200005;
        
        int n = ni();
        long k = nl();
        long[] a = new long[SIZE];
        long[] b = new long[SIZE];
        
        long min = Integer.MAX_VALUE;
        for(int i = 0; i < n; i++) {
            int num = ni();
            a[num]++;
            b[num] += num;
            min = Math.min(min, num);
        }
        
        for(int i = a.length - 2; i >= 0; i--) {
            a[i] += a[i + 1];
            b[i] += b[i + 1];
        }
        
        List<Long> removed = new ArrayList<>();
        for(int i = a.length - 1; i >= min; i--) {
            if(a[i] > 0) {
                long newlyRemoved = b[i] - (a[i] * i);
                removed.add(newlyRemoved);
            }
        }
        
        //System.out.println(removed);
        
        long currentlyRemoved = 0, count = 0;
        for(int i = 1; i < removed.size(); i++) {
            if(removed.get(i) - currentlyRemoved > k) {
                count++;
                currentlyRemoved = removed.get(i - 1);
                //System.out.println(removed.get(i));
            }
        }
        if(removed.get(removed.size() - 1) - currentlyRemoved > 0) {
            count++;
        }
        
        System.out.println(count);
    }
    
    //Reader & Writer
    String nt() throws Exception {
        if (stk == null || !stk.hasMoreTokens())
            stk = new StringTokenizer(br.readLine(), " ");
        return stk.nextToken();
    }

    char[] nc() throws Exception {
        return nt().toCharArray();
    }

    int ni() throws Exception {
        return Integer.parseInt(nt());
    }

    long nl() throws Exception {
        return Long.parseLong(nt());
    }
    
    double nd() throws Exception {
        return Double.parseDouble(nt());
    }
    
    //Some Misc methods
    int get(int l, int r, int[] a) {
        return l == 0 ? a[r] : a[r] - a[l - 1];
    }
    
    void shuffle(int[] a) {
        Random r = new Random();
        for(int i = 0; i < a.length; i++) {
            int idx = r.nextInt(a.length);
            int temp = a[i];
            a[i] = a[idx];
            a[idx] = temp;
        }
    }
    
    void reverse(long[] a) {
        for(int i = 0, j = a.length - 1; i < j; i++, j--) {
            long temp = a[i];
            a[i] = a[j];
            a[j] = temp;
        }
    }
    
    void print(int[] a) {
        System.out.println(Arrays.toString(a));
    }
    
    void print(long[] a) {
        System.out.println(Arrays.toString(a));
    }
}