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).
import java.util.*;
import java.math.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

     //--------------->>>>IF YOU ARE HERE FOR QUICKSORT HACK THEN SORRY NO HACK FOR YOU<<<-------------------

public class a{ 
     static long[] count,count1,count2;
     static boolean[] prime;
     static Node[] nodes,nodes1,nodes2;
     static NodeInt[] nodesInt,nodesInt1;
     static long[] arr;
     static long[][] cost;
     static int[] arrInt,darrInt,farrInt;
     static long[][] dp;
     static char[] ch,ch1;
     static long[] darr,farr;
     static long[][] mat,mat1;
     static boolean[] vis;
     static long x,h;
     static long maxl;
     static double dec;
     static long mx = (long)1e7;
     static long inf = (long)1e15;
     static String s,s1,s2,s3,s4;
     static long minl;   
     static long mod = ((long)(1e9))+7;
     // static int minl = -1;
     // static long n;
     static int n,n1,n2,q,r1,c1,r2,c2;
     static int arr_size = (int)2e5+10;
     static long a;
     static long b;
     static long c;
     static long d;
     static long y,z;
     static int m;
     static int ans;
     static long k;
     static FastScanner sc;
     static String[] str,str1;
     static Set<Integer> set,set1,set2;
     static SortedSet<Long> ss;
     static List<Integer> list,list1,list2,list3;
     static PriorityQueue<Node> pq,pq1;
     static LinkedList<Node> ll,ll1,ll2;
     static Map<Integer,List<Integer>> map1;
     static Map<Long,Integer> map;
     static StringBuilder sb,sb1,sb2;
     static int index;
     static long[] sum;
     static int[] dx = {0,-1,0,1,-1,1,-1,1};
     static int[] dy = {-1,0,1,0,-1,-1,1,1};

     // public static void solve(){

     //    FastScanner sc = new FastScanner();
     //    // int t = sc.nextInt();
     //    int t = 1;
     //    for(int tt = 0 ; tt < t ; tt++){

     //        // s = sc.next();
     //        // s1 = sc.next();

     //        n = sc.nextInt();

     //        m = sc.nextInt();

     //        // int k = sc.nextInt();

     //        // sb = new StringBuilder();

     //        map = new HashMap<>();
     //        map1 = new HashMap<>();

     //        // q = sc.nextInt();
     //        // sb = new StringBuilder();
     //        // long k = sc.nextLong();

     //        // ch = sc.next().toCharArray();

     //        // count = new int[200002];
           
     //        // m = sc.nextInt();

     //        for(int o = 0 ; o < m ; o++){

     //            int l = sc.nextInt()-1;
     //            int r = sc.nextInt()-1;

     //        }

     //    }
        
     // }

     //--------------->>>>IF YOU ARE HERE FOR QUICKSORT HACK THEN SORRY NO HACK FOR YOU<<<-------------------

     public static void solve(){

        int[] count = new int[arr_size];
        long minl = inf;
        for(int i = 0 ; i < n ; i++){
            minl = min(minl,arr[i]);
            count[(int)arr[i]] += 1;
        }

        for(int i = arr_size-2 ; i > -1 ; i--)
            count[i] += count[i+1];

        long curr = 0;
        int ans = 0;
        for(int i = arr_size-1 ; i > minl ; i--){
            curr += count[i];
            if(curr > k){
                curr = count[i];
                ans += 1;
            }
        }
        if(curr > 0)
            ans += 1;
        System.out.println(ans);

     }
        
     public static void main(String[] args) {

            sc = new FastScanner();
            // Scanner sc = new Scanner(System.in);
            // int t = sc.nextInt();
            int t = 1;
            // int l = 1;
            while(t > 0){
                
                // n = sc.nextInt();
                // n = sc.nextLong();
                // k = sc.nextLong();
                // x = sc.nextLong();
                // y = sc.nextLong();
                // z = sc.nextLong();

                // a = sc.nextLong();
                // b = sc.nextLong();
                // c = sc.nextLong();
                // d = sc.nextLong();

                // x = sc.nextLong();
                // y = sc.nextLong();
                // z = sc.nextLong();
                // d = sc.nextLong();

                n = sc.nextInt();

                // n1 = sc.nextInt();

                // m = sc.nextInt();
                // q = sc.nextInt();

                // a = sc.nextLong();
                // b = sc.nextLong();

                k = sc.nextLong();

                // x = sc.nextLong();
                // d = sc.nextLong();

                // s = sc.next();

                // ch = sc.next().toCharArray();
                // ch1 = sc.next().toCharArray();

                // m = sc.nextInt();
                // n = 6;

                arr = new long[n];
                for(int i = 0 ; i < n ; i++){
                    arr[i] = sc.nextLong();
                }

                // arrInt = new int[n];
                // for(int i = 0 ; i < n ; i++){
                //     arrInt[i] = sc.nextInt();
                // }
                // x = sc.nextLong();
                // y = sc.nextLong();
                // ch = sc.next().toCharArray();
                // m = n;
                // m = sc.nextInt();
                // darr = new long[m];
                // for(int i = 0 ; i < m ; i++){
                //     darr[i] = sc.nextLong();
                // }
                // k = sc.nextLong();
                // m = n;
                // darrInt = new int[n];
                // for(int i = 0 ; i < n ; i++){
                //     darrInt[i] = sc.nextInt();
                // }

                // farrInt = new int[m];
                // for(int i = 0; i < m ; i++){
                //     farrInt[i] = sc.nextInt();
                // }

                // m = n;
                // mat = new long[n][m];
                // for(int i = 0 ; i < n ; i++){
                //     for(int j = 0 ; j < m ; j++){
                //         mat[i][j] = sc.nextLong();
                //     }
                // }

                // m = n;
                // mat = new char[n][m];
                // for(int i = 0 ; i < n ; i++){
                //     String s = sc.next();
                //     for(int j = 0 ; j < m ; j++){
                //         mat[i][j] = s.charAt(j);
                //     }
                // }

                // str = new String[n];
                // for(int i = 0 ; i < n ; i++)
                //     str[i] = sc.next();

                // nodes = new Node[n];
                // for(int i = 0 ; i < n ;i++)
                //     nodes[i] = new Node(sc.nextLong(),sc.nextLong());

                // nodesInt = new NodeInt[n];
                // for(int i = 0 ; i < n ;i++)
                //     nodesInt[i] = new NodeInt(sc.nextInt(),sc.nextInt(),i);

                 solve();       
                 t -= 1;
            }

     }

    public static int log(long n,long base){

         if(n == 0 || n == 1)
             return 0;

         if(n == base)
             return 1;

         double num = Math.log(n);
         double den = Math.log(base);

         if(den == 0)
             return 0;

         return (int)(num/den);
     }

    public static boolean isPrime(long n) { 
    // Corner cases 
        if (n <= 1)  
            return false; 

        if (n <= 3)  
            return true; 
      
        // This is checked so that we can skip  
        // middle five numbers in below loop 
        if (n%2 == 0 || n%3 == 0) 
            return false; 
      
        for (int i=5; i*i<=n; i=i+6) 
            if (n%i == 0 || n%(i+2) == 0) 
               return false; 
      
        return true; 
    } 

    public static long gcd(long a, long b)
    {
      if (b == 0)
        return a;
      return gcd(b, a % b); 
    }

    public static long lcm(long a, long b)
    {
      return (b/gcd(b, a % b)) * a; 
    }

     public static long mod_inverse(long a,long mod){
        long x1=1,x2=0;
        long p=mod,q,t;
        while(a%p!=0){
          q = a/p;
          t = x1-q*x2;
          x1=x2; x2=t;
          t=a%p;
          a=p; p=t;
        }
        return x2<0 ? x2+mod : x2;
    }

     public static void swap(long[] curr,int i,int j){
         long temp = curr[j];
         curr[j] = curr[i];
         curr[i] = temp;
     }

    static final Random random=new Random();

    static void ruffleSortLong(long[] a) {
        int n=a.length;//shuffle, then sort 
        for (int i=0; i<n; i++) {
            int oi=random.nextInt(n);
            long temp=a[oi];
            a[oi]=a[i]; a[i]=temp;
        }
        Arrays.sort(a);
    }

    static void ruffleSortInt(int[] a) {
        int n=a.length;//shuffle, then sort 
        for (int i=0; i<n; i++) {
            int oi=random.nextInt(n);
            int temp=a[oi];
            a[oi]=a[i]; a[i]=temp;
        }
        Arrays.sort(a);
    }
    
    static void ruffleSortChar(char[] a) {
        int n=a.length;//shuffle, then sort 
        for (int i=0; i<n; i++) {
            int oi=random.nextInt(n);
            char temp=a[oi];
            a[oi]=a[i]; a[i]=temp;
        }
        Arrays.sort(a);
    }

    static long binomialCoeff(long n, long k){ 

        long res = 1; 
  
        // Since C(n, k) = C(n, n-k) 
        if (k > n - k) 
            k = n - k; 
  
        // Calculate value of 
        // [n * (n-1) *---* (n-k+1)] / [k * (k-1) *----* 1] 
        for (long i = 0; i < k; ++i) { 
            res = (res*(n - i)); 
            res = (res/(i + 1)); 
        } 

        return res; 
    } 

    static long[] fact;

    public static long inv(long n){
        return power(n, mod-2);
    }

    public static void fact(int n){
        fact = new long[n+1];
        fact[0] = 1;
        for(int j = 1;j<=n;j++)
            fact[j] = (fact[j-1]*(long)j)%mod;               
    }

    public static long binom(int n, int k){
        fact(n+1);
        long prod = fact[n];
        prod*=inv(fact[n-k]);
        prod%=mod;
        prod*=inv(fact[k]);
        prod%=mod;
        return prod;    
    }

    static long power(long x, long y){
        if (y == 0)
            return 1;
        if (y%2 == 1)
            return (x*power(x, y-1))%mod;
        return power((x*x)%mod, y/2)%mod;
    }

    public static long pow(long n,long p,long m){
     long  result = 1;
      if(p==0)
        return 1;
          
    while(p!=0)
    {
        if(p%2==1)
            result *= n;
        if(result>=m)
        result%=m;
        p >>=1;
        n*=n;
        if(n>=m)
        n%=m;
    }
    return result;
    }

    static void sieve(int n){ 

        prime = new boolean[n+1]; 
        for(int i=2;i<n;i++) 
            prime[i] = true; 
          
        for(int p = 2; p*p <=n; p++) 
        { 
            if(prime[p] == true) 
            { 
                for(int i = p*p; i <= n; i += p) 
                    prime[i] = false; 
            } 
        } 

    }

    static class Node{
        int first;
        int second;
        Node(int f,int s){
            this.first = f;
            this.second = s;
        }
    }

    static class NodeInt{
        int first;
        int second;
        int third;
        NodeInt(int f,int s,int third){
            this.first = f;
            this.second = s;
            this.third = third;
        }
    }

    static long abs(long a){
        return Math.abs(a);
    }

    static int abs(int a){
        return Math.abs(a);
    }

    static int max(int a,int b){
    if(a>b)
            return a;
    else
            return b;
    }
 
    static int min(int a,int b){
    if(a>b)
            return b;
    else 
            return a;
    }
 
    static long max(long a,long b){
    if(a>b)
            return a;
    else
            return b;
    }
 
    static long min(long a,long b){
    if(a>b)
            return b;
    else 
            return a;
    }

    static long sq(long num){
        return num*num;
    }

     static class FastScanner {

                BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
                StringTokenizer st=new StringTokenizer("");
                String next() {
                        while (!st.hasMoreTokens())
                                try {
                                        st=new StringTokenizer(br.readLine());
                                } catch (IOException e) {
                                        e.printStackTrace();
                                }
                        return st.nextToken();
                }
                
                int nextInt() {
                        return Integer.parseInt(next());
                }
                int[] readArray(int n) {
                        int[] a=new int[n];
                        for (int i=0; i<n; i++) a[i]=nextInt();
                        return a;
                }
                long nextLong() {
                        return Long.parseLong(next());
                }
        }

}