Natasha is going to fly to Mars. She needs to build a rocket, which consists of several stages in some order. Each of the stages is defined by a lowercase Latin letter. This way, the rocket can be described by the string — concatenation of letters, which correspond to the stages.

There are n stages available. The rocket must contain exactly k of them. Stages in the rocket should be ordered by their weight. So, after the stage with some letter can go only stage with a letter, which is at least two positions after in the alphabet (skipping one letter in between, or even more). For example, after letter 'c' can't go letters 'a', 'b', 'c' and 'd', but can go letters 'e', 'f', ..., 'z'.

For the rocket to fly as far as possible, its weight should be minimal. The weight of the rocket is equal to the sum of the weights of its stages. The weight of the stage is the number of its letter in the alphabet. For example, the stage 'a 'weighs one ton,' b 'weighs two tons, and' z' — 26 tons.

Build the rocket with the minimal weight or determine, that it is impossible to build a rocket at all. Each stage can be used at most once.

Input

The first line of input contains two integers — n and k (1 ≤ k ≤ n ≤ 50) – the number of available stages and the number of stages to use in the rocket.

The second line contains string s, which consists of exactly n lowercase Latin letters. Each letter defines a new stage, which can be used to build the rocket. Each stage can be used at most once.

Output

Print a single integer — the minimal total weight of the rocket or -1, if it is impossible to build the rocket at all.

Examples

Input

5 3
xyabd


Output

29

Input

7 4
problem


Output

34

Input

2 2
ab


Output

-1

Input

12 1
abaabbaaabbb


Output

1

Note

In the first example, the following rockets satisfy the condition:

  * "adx" (weight is 1+4+24=29);
  * "ady" (weight is 1+4+25=30);
  * "bdx" (weight is 2+4+24=30);
  * "bdy" (weight is 2+4+25=31).



Rocket "adx" has the minimal weight, so the answer is 29.

In the second example, target rocket is "belo". Its weight is 2+5+12+15=34.

In the third example, n=k=2, so the rocket must have both stages: 'a' and 'b'. This rocket doesn't satisfy the condition, because these letters are adjacent in the alphabet. Answer is -1.
//package geometry;
import java.io.*;
import java.util.*;
import java.util.Map.Entry;
import java.text.*;
import java.math.*;
import java.util.regex.*;
import javafx.scene.layout.Priority;
import java.awt.Point;
/**
 *
 * @author prabhat // use stringbuilder, priorityQueue
 */
   public class  point4{
   public  static long[] BIT;
   public  static long[] tree;
   public  static long[] sum;
   public  static int mod=1000000007;
   public  static int[][] dp;
   public  static boolean[][] isPalin;
   public  static int max1=1000010;
   public  static int[][] g;
   public  static LinkedList<Pair> l[];
   public  static int n,m,q,k,t,arr[],b[],cnt[],chosen[],pos[],val[],blocksize,count;
   public  static long V[],low,high,min=Long.MAX_VALUE,cap[],has[],ans,max;
   public  static ArrayList<Integer> adj[],al;
   public  static TreeSet<Integer> ts;
   public  static   char s[];
   public  static int depth,mini,maxi;
   public  static boolean visit[][],isPrime[],used[];
   public  static int[][] dist;
   public  static ArrayList<Integer>prime;
   public  static int[] x={0,1};
   public  static int[] y={-1,0};
   public  static ArrayList<Integer> divisor[]=new ArrayList[1500005];
   public  static  int[][] subtree,parent,mat;
   public  static  TreeMap<Integer,Integer> tm;
   public  static LongPoint[] p;
   public  static int[][] grid,memo;
   public  static ArrayList<Pair> list;
   public  static TrieNode root;
   public  static  LinkedHashMap<String,Integer> map;
   public  static ArrayList<String> al1;
   public  static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
   public  static void main(String[] args) throws Exception
   {
   	   InputReader in = new InputReader(System.in);
	   PrintWriter pw=new PrintWriter(System.out);
	   n=in.ii();
	   k=in.ii();
	   s=in.is().toCharArray();
	   Arrays.sort(s);
	   ans=Long.MAX_VALUE;
	   for(int i=0;i<n;i++)
	   {
		   
		   v(i,1,(s[i]-'a')+1);
	   }
	   pw.println(ans==Long.MAX_VALUE?-1:ans);
	 /* n=in.ii();
	  long ans=0;
	  Point[] p=new Point[n];
	  for(int i=0;i<n;i++)
	   {
		  p[i]=new Point(in.ii(),in.ii());
	   }
	   for(int i=0;i<n;i++)
	   {
		   if(orient(p[i],p[(i+1)%n],p[(i+2)%n])<0)ans++;
	   }
	   pw.println(ans);*/
	   pw.close();
}
static void v(int indx,int cnt,int sum)
{
	if(cnt>k)return;
	if(cnt==k)
	{
		ans=Math.min(ans,sum);
		return;
	}
	else{
		for(int j=indx+1;j<n;j++)
		{
			int y=s[j]-s[indx];
			if(y>=2)
			{
				v(j,cnt+1,sum+(s[j]-'a')+1);
			}
		}
	}
}
static int orient(Point a,Point b,Point c)
{
	//return (int)(c.x-a.x)*(int)(b.y-a.y)-(int)(c.y-a.y)*(int)(b.x-a.x);
	Point p1=c.minus(a);
	Point p2=b.minus(a);
	return (int)(p1.cross(p2));
}
public static class Polygon {

	static final double EPS = 1e-15;
	public int n;
	public Point p[];

	Polygon(int n, Point x[]) {
		this.n = n;
		p = Arrays.copyOf(x, n);
	}

	long area(){ //returns 2 * area
		long ans = 0;
		for(int i = 1; i + 1 < n; i++)
			ans += p[i].minus(p[0]).cross(p[i + 1].minus(p[0]));
		return ans;
	}
	
	boolean PointInPolygon(Point q) {
		boolean c = false;
		for (int i = 0; i < n; i++){
			int j = (i+1)%n;
			if ((p[i].y <= q.y && q.y < p[j].y || 
					p[j].y <= q.y && q.y < p[i].y) &&
					q.x < p[i].x + (p[j].x - p[i].x) * (q.y - p[i].y) / (p[j].y - p[i].y))
			c = !c;
		 }
		return c;
	}

		// determine if point is on the boundary of a polygon
	boolean PointOnPolygon(Point q) {
		 for (int i = 0; i < n; i++)
		 if (ProjectPointSegment(p[i], p[(i+1)%n], q).dist(q) < EPS)
			 return true;
		 return false;
	}
	
	// project point c onto line segment through a and b
	Point ProjectPointSegment(Point a, Point b, Point c) {
	  double r = b.minus(a).dot(b.minus(a));
	  if (Math.abs(r) < EPS) return a;
	  r = c.minus(a).dot(b.minus(a))/r;
	  if (r < 0) return a;
	  if (r > 1) return b;
	  return a.plus(b.minus(a).mul(r));
	}
}

public static class Point {
	public double x, y;

	public Point(double x, double y) {
		this.x = x;
		this.y = y;
	}

	public Point minus(Point b) {
		return new Point(x - b.x, y - b.y);
	}
	
	public Point plus(Point a){
		return new Point(x + a.x, y + a.y);
	}

	public double cross(Point b) {
		return (double)x * b.y - (double)y * b.x;
	}

	public double dot(Point b) {
		return (double)x * b.x + (double)y * b.y;
	}
	
	public Point mul(double r){
		return new Point(x * r, y * r);
	}
	
	public double dist(Point p){
		return Math.sqrt(fastHypt( x - p.x , y - p.y));
	}
	
	public double fastHypt(double x, double y){
		return x * x + y * y;
	}
}
static class Query implements Comparable<Query>{
	int index,k;
	int L;
	int R;
	public Query(){}
	public Query(int a,int b,int index)
	{
	  this.L=a;
	  this.R=b;
	  this.index=index;
	}
   public int compareTo(Query o)
   {
	  if(L/blocksize!=o.L/blocksize)return L/blocksize-o.L/blocksize;
	  else return R-o.R;
   }
 
 }

static double dist(Point p1,Point p2)
{
	return Math.sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y));
}

static class coder {
	int indx;
	String name;
	coder(int indx,String name)
	{
		this.indx=indx;
		this.name=name;
	}
}
static class TrieNode
{
	int value;  // Only used in leaf nodes
	int freq;
	TrieNode[] arr =  new TrieNode[2];
	public TrieNode() {
		value = 0;
		freq=0;
		arr[0] = null;
		arr[1] = null;
	}
}
static void insert(int pre_xor,int add)
{
	TrieNode temp = root;
	
	// Start from the msb, insert all bits of
	// pre_xor into Trie
	for (int i=31; i>=0; i--)
	{
		// Find current bit in given prefix
		int val = (pre_xor & (1<<i)) >=1 ? 1 : 0;
		
		// Create a new node if needed
		if (temp.arr[val] == null)
			temp.arr[val] = new TrieNode();
		
		temp = temp.arr[val];
		temp.freq+=add;
	}
  
	// Store value at leaf node
	//temp.value = pre_xor;
}

static long query(int pre_xor)
{
	TrieNode temp = root;
	long ans=0;
	for (int i=31; i>=0; i--)
	{
		// Find current bit in given prefix
		int val = (pre_xor & (1<<i)) >= 1 ? 1 : 0;
		
		if(temp.arr[1-val]!=null&&temp.arr[1-val].freq>0)
		{
			ans|=1l<<i;
			temp=temp.arr[1-val];
		}
        else if(temp.arr[val]!=null&&temp.arr[val].freq>0)
            temp=temp.arr[val];
		else break;
	}
	return ans;
}
static void update(int indx,long val)
   {
	   while(indx<max1)
	   {
		   BIT[indx]+=val;
		   indx+=(indx&(-indx));
	   }
	   
   }
static long query1(int indx)
   {
	   long sum=0;
	   while(indx>0)
	   {
		  sum+=BIT[indx];
		   indx-=(indx&(-indx));
	   }
	   return sum;
	}
   

static int gcd(int a, int b) 
{
	int res=0;
	while(a!=0)
	{
		res=a;
		a=b%a;
		b=res;
	}
	return b;
}
static slope getSlope(Point p, Point q)
	{
		int dx = (int)(q.x - p.x), dy = (int)(q.y - p.y);
		int g = gcd(dx, dy);
		return new slope(dy / g, dx / g);
	}
	
static class slope implements Comparable<slope>
{
	int x,y;
	public slope(int y,int x)
	{
		this.x=x;
		this.y=y;
	}
	public int compareTo(slope s)
	{
		if(s.y!=y)return y-s.y;
	return x-s.x;
	}
}

static class Ball implements Comparable
	{
		int r;
		int occ;
		public Ball(int r,int occ)
		{
			this.r = r;
			this.occ = occ;
		}
		@Override
		public int compareTo(Object o) {
			Ball b = (Ball) o;
			return b.occ-this.occ;
		}
	}

static class E implements Comparable<E>{
	int x,y;
	char c;
	E(int  x,int y,char c)
	{
		this.x=x;
		this.y=y;
		this.c=c;
	}
	public int compareTo(E o)
	{
		if(x!=o.x)return o.x-x;
		else return y-o.y;
		
	}
}

static ArrayList<String> dfs(String s,String[] sarr,HashMap<String, ArrayList<String>> map)
{
   if(map.containsKey(s))return map.get(s);
   ArrayList<String> res=new ArrayList<>();
   if(s.length()==0)
   {
	   res.add("");
	   return res;
   }

   for(String word:sarr)
   {
	   if(s.startsWith(word))
	   {
		   ArrayList<String > sub=dfs(s.substring(word.length()),sarr,map);
		   for(String s2:sub)
		   {
			   res.add(word+ (s2.isEmpty() ? "" : " ")+s2);
		   }
	   }
   }
   map.put(s,res);
   return res;
}
static class SegmentTree{
  
  int n;
  int max_bound;
 
  public SegmentTree(int n)
  {
	
	  this.n=n;
	  tree=new long[4*n+1];
	  build(1,0,n-1);
  }
void build(int c,int s,int e)
{
   if(s==e)
   {
	   tree[c]=arr[s];
	   return ;
   }

   int mid=(s+e)>>1;
   build(2*c,s,mid);
   build(2*c+1,mid+1,e);
   tree[c]=(tree[2*c]&tree[2*c+1]);
}
void put(int c,int s, int e,int l,int r,int  v) {
	if(l>e||r<s||s>e)return ;
	if (s == e) 
	{
		tree[c] = arr[s]^v;
		return;
	}
	int mid = (s + e) >> 1;
	if (l>mid) put(2*c+1,m+1, e , l,r, v);
	else if(r<=mid)put(2*c,s,m,l,r , v);
	else{
      
	}
	
}
long query(int c,int s,int e,int l,int r)
{
   if(e<l||s>r)return 0L;

   if(s>=l&&e<=r)
   {
	return tree[c];
   }

	int mid=(s+e)>>1;
	long ans=(1l<<30)-1;
	if(l>mid)return query(2*c+1,mid+1,e,l,r);
	else if(r<=mid)return query(2*c,s,mid,l,r);
	else{
		return query(2*c,s,mid,l,r)&query(2*c+1,mid+1,e,l,r);
	}

 }
}  

   
   public static ListNode removeNthFromEnd(ListNode a, int b) {
       
    int cnt=0;
	ListNode ra1=a;
	ListNode ra2=a;
	while(ra1!=null){ra1=ra1.next; cnt++;}
	
	if(b>cnt)return a.next;
	else if(b==1&&cnt==1)return null;
	else{
		int y=cnt-b+1;
		int u=0;
		ListNode prev=null;
		while(a!=null)
		{
			u++;
		   if(u==y)
		   {
			   if(a.next==null)prev.next=null;
			   else
			   {
				   if(prev==null)return ra2.next;
				   prev.next=a.next;
				   a.next=null;
			   }
			   break;
		   }
		   prev=a;
		   a=a.next;
		}
	}
	return ra2;
}
   static ListNode rev(ListNode a)
   {
       ListNode prev=null;
       ListNode cur=a;
       ListNode next=null;
       while(cur!=null)
       {
           next=cur.next;
           cur.next=prev;
           prev=cur;
           cur=next;
       }
       return prev;
   }
  
  static class ListNode {
	     public int val;
	     public ListNode next;
	     ListNode(int x) { val = x; next = null; }
	 }
  
 
   public static String add(String s1,String s2)
   {
	   int n=s1.length()-1;
	   int m=s2.length()-1;
	   int rem=0;
	   int carry=0;
	   int i=n;
	   int j=m;
	   String ans="";
	   while(i>=0&&j>=0)
	   {
		 int c1=(int)(s1.charAt(i)-'0');
		 int c2=(int)(s2.charAt(j)-'0');
		 int sum=c1+c2;
		 sum+=carry;
		 rem=sum%10;
		 carry=sum/10;
         ans=rem+ans;
		  i--; j--;
		  
	   }
	   while(i>=0)
	   {
		int c1=(int)(s1.charAt(i)-'0');
	
		int sum=c1;
		sum+=carry;
		rem=sum%10;
		carry=sum/10;
		ans=rem+ans;
		i--;
	   }
	   while(j>=0)
	   {
	
		int c2=(int)(s2.charAt(j)-'0');
		int sum=c2;
		sum+=carry;
		rem=sum%10;
		carry=sum/10;
		ans=rem+ans;
		j--;
	   }

	   if(carry>0)ans=carry+ans;
	   return ans;
   }
   public static String[] multiply(String A, String B) {
	int lb=B.length();
	char[] a=A.toCharArray();
	char[] b=B.toCharArray();
	String[] s=new String[lb];
	int cnt=0;
	int y=0;
	String s1="";
q=0;
	for(int i=b.length-1;i>=0;i--)
	{
		int rem=0;
		int carry=0;
		
	
		for(int j=a.length-1;j>=0;j--)
		{
			int mul=(int)(b[i]-'0')*(int)(a[j]-'0');
			mul+=carry;
			rem=mul%10;
			carry=mul/10;
			s1=rem+s1;
		}
		s1=carry+s1;
		s[y++]=s1;
		q=Math.max(q,s1.length());
		s1="";
		for(int i1=0;i1<y;i1++)s1+='0';
		
	}
	return s;
}
   public static long nCr(long total, long choose)
   {
	   if(total < choose)
		   return 0;
	   if(choose == 0 || choose == total)
		   return 1;
	   return nCr(total-1,choose-1)+nCr(total-1,choose);
   }
 
 
   static int get(long s)
   {
	  int ans=0;
	  for(int i=0;i<n;i++)
	  {
		  if(p[i].x<=s&&s<=p[i].y)ans++;
	  }
	  return ans;
   }
   static class LongPoint {
	public long x;
	public long y;

	public LongPoint(long x, long y) {
		this.x = x;
		this.y = y;
	}

	public LongPoint subtract(LongPoint o) {
		return new LongPoint(x - o.x, y - o.y);
	}

	public long cross(LongPoint o) {
		return x * o.y - y * o.x;
	}

}
    static int CountPs(String s,int n)
       {
    	boolean b=false;
    	     char[] S=s.toCharArray();
	       int[][] dp=new int[n][n];
	       boolean[][] p=new boolean[n][n];
	       for(int i=0;i<n;i++)p[i][i]=true;
	     
	       for(int i=0;i<n-1;i++)
	       {
	    	   if(S[i]==S[i+1])
	    	   {
	    		p[i][i+1]=true;
	    		dp[i][i+1]=0;
	    		b=true;
	    	   }
	       }
	    
	       for(int gap=2;gap<n;gap++)
	       {
	    	   for(int i=0;i<n-gap;i++)
	    	   {
	    		   int j=gap+i;
	    		   if(S[i]==S[j]&&p[i+1][j-1]){p[i][j]=true;}
	    		  
	    		  if(p[i][j])
	    			   dp[i][j]=dp[i][j-1]+dp[i+1][j]+1-dp[i+1][j-1];
	    		   
	    		   else if(!p[i][j]) dp[i][j]=dp[i][j-1]+dp[i+1][j]-dp[i+1][j-1];
	    		  
	    		   //if(dp[i][j]>=1)
                             //  return true;
	    	   }
	       }
	      
	   // return b; 
    return dp[0][n-1];
	       
    }
  
  
  static void Seive()
  {
      isPrime=new boolean[1500005];
      Arrays.fill(isPrime,true);
	 for(int i=0;i<1500005;i++){divisor[i]=new ArrayList<>();}
	 int u=0;
	 prime=new ArrayList<>();
      for(int i=2;i<=(1500000);i++)
      {
         
          if(isPrime[i])
          {
			prime.add(i);
              for(int j=i;j<1500000;j+=i)
              {
                  
                  divisor[j].add(i);
                  
                  isPrime[j]=false;
              }
         /*    for(long x=(divCeil(low,i))*i;x<=high;x+=i)
             {
                 divisor[(int)(x-low)].add(i*1L);
             }*/
              
          }
      }
      
  }
  static long divCeil(long a,long b)
  {
      return (a+b-1)/b;
  }
  static long root(int pow, long x) {
        long candidate = (long)Math.exp(Math.log(x)/pow);
        candidate = Math.max(1, candidate);
        while (pow(candidate, pow) <= x) {
            candidate++;
        }
        return candidate-1;
    }
    
    static long pow(long x, int pow)
    {
        long result = 1;
        long p = x;
        while (pow > 0) {
            if ((pow&1) == 1) {
                if (result > Long.MAX_VALUE/p) return Long.MAX_VALUE;
                result *= p;
            }
            pow >>>= 1;
            if (pow > 0 && p >= 4294967296L) return Long.MAX_VALUE;
            p *= p;
        }
        return result;
    }
  
  static boolean valid(int i,int j)
  {
	  if(i>=0&&i<n&&j>=0&&j<m)return true;
	  return false;
  }
  private static class DSU{
		int[] parent;
		int[] rank;
		int cnt;
		public DSU(int n){
			parent=new int[n];
			rank=new int[n];
			for(int i=0;i<n;i++){
				parent[i]=i;
				rank[i]=1;
			}
			cnt=n;
		}
		int find(int i){
	        while(parent[i] !=i){
	        	parent[i]=parent[parent[i]];
	        	i=parent[i];
	        }
	        return i;
	    }
		int Union(int x, int y){
	        int xset = find(x);
	        int yset = find(y);
	        if(xset!=yset)
	        	cnt--;
	        if(rank[xset]<rank[yset]){
	        	parent[xset] = yset;
		        rank[yset]+=rank[xset];
		        rank[xset]=0;
		        return yset;
	        }else{
	        	parent[yset]=xset;
	        	rank[xset]+=rank[yset];
	        	rank[yset]=0;
	        	return xset;
	        }
	    }
	}
  public static int[][] packU(int n, int[] from, int[] to, int max) {
	    
	    int[][] g = new int[n][];
	    int[] p = new int[n];
	    for (int i = 0; i < max; i++) p[from[i]]++;
	    for (int i = 0; i < max; i++) p[to[i]]++;
	    for (int i = 0; i < n; i++) g[i] = new int[p[i]];
	    for (int i = 0; i < max; i++) {
	        g[from[i]][--p[from[i]]] = to[i];
	        g[to[i]][--p[to[i]]] = from[i];
	    }
	    return g;
	}
	public static int[][] parents3(int[][] g, int root) {
	    int n = g.length;
	    int[] par = new int[n];
	    Arrays.fill(par, -1);

	    int[] depth = new int[n];
	    depth[0] = 0;

	    int[] q = new int[n];
	    q[0] = root;
	    for (int p = 0, r = 1; p < r; p++) {
	        int cur = q[p];
	        for (int nex : g[cur]) {
	            if (par[cur] != nex) {
	                q[r++] = nex;
	                par[nex] = cur;
	                depth[nex] = depth[cur] + 1;
	            }
	        }
	    }
	    return new int[][]{par, q, depth};
	}
	public static int lower_bound(int[] nums, int target) {
        int low = 0, high = nums.length - 1;
        while (low < high) {
            int mid = low + (high - low) / 2;
            if (nums[mid] < target)
                low = mid + 1;
            else
                high = mid;
        }
        return nums[low] == target ? low : -1;
    }

    public static int upper_bound(int[] nums, int target) {
        int low = 0, high = nums.length - 1;
        while (low < high) {
            int mid = low + (high + 1 - low) / 2;
            if (nums[mid] > target)
                high = mid - 1;
            else
                low = mid;
        }
        return nums[low] == target ? low : -1;
    }
  public static boolean palin(String s)
	{
	   int i=0;
	   int j=s.length()-1;
	   while(i<j)
	   {
		   if(s.charAt(i)==s.charAt(j))
		   {
			   i++;
			   j--;
		   }
		   else return false;     
	   }
	   return true;
	}
	
 
static int lcm(int a,int b)
{
	return (a*b)/(gcd(a,b));
}

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;
}

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

     }




static class Edge implements Comparator<Edge> {
	private int u;
	private int v;
	private long w;
	public Edge() {
	}
	public Edge(int u, int v, long w) {
		this.u=u;
		this.v=v;
		this.w=w;
	}
	public int getU() {
		return u;
	}
	public void setU(int u) {
		this.u = u;
	}
	public int getV() {
		return v;
	}
	public void setV(int v) {
		this.v = v;
	}
	public long getW() {
		return w;
	}
	public void setW(int w) {
		this.w = w;
	      }
	public long compareTo(Edge e)
	  {
		return (this.getW() - e.getW());
	}

        @Override
        public int compare(Edge o1, Edge o2) {
            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
        }
	
}



static class Pair implements Comparable<Pair>
{
	int x,y;
	Pair (int a,int b)
	{
		this.x=a;
		this.y=b;
	}

	public int compareTo(Pair o) {
		// TODO Auto-generated method stub
		if(this.x!=o.x)
		return -Integer.compare(this.x,o.x);
		else
			return -Integer.compare(this.y, o.y);
		//return 0;
	}
	public boolean equals(Object o) {
       if (o instanceof Pair) {
           Pair p = (Pair)o;
           return p.x == x && p.y == y;
       }
       return false;
   }
   public int hashCode() {
       return new Integer(x).hashCode() * 31 + new Integer(y).hashCode();
   }
}

static  class InputReader
{
   private InputStream stream;
   private byte[] buf = new byte[1024];

   private SpaceCharFilter filter;
    byte inbuffer[] = new byte[1024];
   int lenbuffer = 0, ptrbuffer = 0;
    final int M = (int) 1e9 + 7;
   int md=(int)(1e7+1);
    int[] SMP=new int[md];
   final double eps = 1e-6;
   final double pi = Math.PI;

	PrintWriter out;
   String check = "";
 InputStream   obj = check.isEmpty() ? System.in : new ByteArrayInputStream(check.getBytes());
   public InputReader(InputStream stream)
   {
       this.stream = stream;
   }

    int readByte() {
	        if (lenbuffer == -1) throw new InputMismatchException();
	        if (ptrbuffer >= lenbuffer) {
	            ptrbuffer = 0;
	            try {
	                lenbuffer = obj.read(inbuffer);
	            } catch (IOException e) {
	                throw new InputMismatchException();
	            }
	        }
	        if (lenbuffer <= 0) return -1;
	        return inbuffer[ptrbuffer++];
   }

   public  int read()
   {
       int c = read();
       while (isSpaceChar(c))
           c = read();
       int sgn = 1;
       if (c == '-')
       {
           sgn = -1;
           c = read();
       }
       int res = 0;
       do
       {
           if (c < '0' || c > '9')
               throw new InputMismatchException();
           res *= 10;
           res += c - '0';
           c = read();
       } while (!isSpaceChar(c));
       return res * sgn;
   }

   String is() {
	        int b = skip();
	        StringBuilder sb = new StringBuilder();
	        while (!(isSpaceChar(b))) // when nextLine, (isSpaceChar(b) && b!=' ')
	        {
	            sb.appendCodePoint(b);
	            b = readByte();
	        }
	        return sb.toString();
   }
   public   int ii() {
	        int num = 0, b;
	        boolean minus = false;
	        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')) ;
	        if (b == '-') {
	            minus = true;
	            b = readByte();
	        }
	        while (true) {
	            if (b >= '0' && b <= '9') {
	                num = num * 10 + (b - '0');
	            } else {
	                return minus ? -num : num;
	            }
	            b = readByte();
	        }
   }
 public   long il() {
	        long num = 0;
	        int b;
	        boolean minus = false;
	        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')) ;
	        if (b == '-') {
	            minus = true;
	            b = readByte();
	        }
	        while (true) {
	            if (b >= '0' && b <= '9') {
	                num = num * 10 + (b - '0');
	            } else {
	                return minus ? -num : num;
	            }
	            b = readByte();
	        }
   }
   
	    boolean isSpaceChar(int c) {
	        return (!(c >= 33 && c <= 126));
	       }

	      int skip()
	        {
	        int b;
	        while ((b = readByte()) != -1 && isSpaceChar(b)) ;
	        return b;
	        }

	    float nf() {
	        return Float.parseFloat(is());
	    }

	    double id() {
	        return Double.parseDouble(is());
	    }

	    char ic() {
	        return (char) skip();
	    }

	    int[] iia(int n) {
	        int a[] = new int[n];
	        for (int i = 0; i<n; i++) a[i] = ii();
	        return a;
	    }

	    long[] ila(int n) {
	        long a[] = new long[n];
	        for (int i = 0; i <n; i++) a[i] = il();
	        return a;
	    }

	    String[] isa(int n) {
	        String a[] = new String[n];
	        for (int i = 0; i < n; i++) a[i] = is();
	        return a;
	    }


		 long mul(long a, long b) { return a * b % M; }

			long div(long a, long b)
				 {
					return mul(a, pow(b, M - 2));

		           }



	    double[][] idm(int n, int m) {
	        double a[][] = new double[n][m];
	        for (int i = 0; i < n; i++) for (int j = 0; j < m; j++) a[i][j] = id();
	        return a;
	        }

	    int[][] iim(int n, int m) {
	        int a[][] = new int[n][m];
	        for (int i = 0; i < n; i++) for (int j = 0; j <m; j++) a[i][j] = ii();
	        return a;
          }


   public String readLine() {
       int c = read();
       while (isSpaceChar(c))
           c = read();
       StringBuilder res = new StringBuilder();
       do {
           res.appendCodePoint(c);
           c = read();
       } while (!isEndOfLine(c));
       return res.toString();
   }

   public interface SpaceCharFilter
   {
       public boolean isSpaceChar(int ch);
   }
   public boolean isEndOfLine(int c) {
       return c == '\n' || c == '\r' || c == -1;
   }
}

}
