Problem: You have a playlist consisting of n songs. The i-th song is characterized by two numbers t_i and b_i — its length and beauty respectively. The pleasure of listening to set of songs is equal to the total length of the songs in the set multiplied by the minimum beauty among them. For example, the pleasure of listening to a set of 3 songs having lengths [5, 7, 4] and beauty values [11, 14, 6] is equal to (5 + 7 + 4) ⋅ 6 = 96.

You need to choose at most k songs from your playlist, so the pleasure of listening to the set of these songs them is maximum possible.

Input

The first line contains two integers n and k (1 ≤ k ≤ n ≤ 3 ⋅ 10^5) – the number of songs in the playlist and the maximum number of songs you can choose, respectively.

Each of the next n lines contains two integers t_i and b_i (1 ≤ t_i, b_i ≤ 10^6) — the length and beauty of i-th song.

Output

Print one integer — the maximum pleasure you can get.

Examples

Input


4 3
4 7
15 1
3 6
6 8


Output


78


Input


5 3
12 31
112 4
100 100
13 55
55 50


Output


10000

Note

In the first test case we can choose songs {1, 3, 4}, so the total pleasure is (4 + 3 + 6) ⋅ 6 = 78.

In the second test case we can choose song 3. The total pleasure will be equal to 100 ⋅ 100 = 10000.

Solution (in JAVA):

Solution:
//package clipse;


import java.util.*;
import java.util.function.Function;
import java.util.stream.Collectors;



import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.*;
import java.math.*;


public class C
{
	
	static StringBuilder sb;
	
	//static long dp[][];
	
	static long pre[];
	static int A[];
	static int n;
	static int cnt[];
	static int portal=0;
	
	
	static void solve()
   {
		StringBuffer sb=new StringBuffer();
		int n=i();
		int k=i();
		pair A[]=new pair[n];
		
		
		PriorityQueue<Long>pq=new PriorityQueue<>();
		
		for(int i=0;i<n;i++) 
		{
			A[i]=new pair(l(),l());
			
		}
		
		Arrays.sort(A);
		
		
		
		long ans=Long.MIN_VALUE;
		
		long presum=0;
		
		long min=Long.MAX_VALUE;
		
		
		for(int i=n-1;i>=0;i--)
		{
			
			pq.add(A[i].x);
			
			presum+=A[i].x;
			
			if(pq.size()>k)
			{
				long pol=(long)pq.poll();
				presum-=pol;
			}
			
			ans=(long)Math.max(ans,(long)presum*1L*(long)A[i].y);
			
			
			
		}
		
		
		
		
		System.out.println(ans);
		
		
		
		

		
		
		
   }

	
		
		
		
	
	

	 public static void main(String[] args)
	    {
		 
		 int testcase=1;
		 		
	         sb=new StringBuilder();
	        int tmp=testcase;
	         while(testcase-->0)
	         {
	        	 
	        	 solve();
	         }
	         
	         System.out.println(sb);
	         
	    }
	 
	 
	 //*********************************Disjoint set union*************************//
	 static class dsu
	 {
		 int parent[];
		 int size[];
		 dsu(int n)
		 {
			 parent=new int[n];
			 size=new int[n];
			 Arrays.fill(size,-1);
			 for(int i=0;i<n;i++)
				 parent[i]=-1;
		 }
		 int find(int a)
		 {
			 if(parent[a]<0)
				 return a;
			 else
			 {
				 int x=find(parent[a]);
				 parent[a]=x;
				 return x;
			 }
		 }
		 void merge(int a,int b)
		 {
			 a=find(a);
			 b=find(b);
			 if(a==b)
				 return;
			 parent[b]=a;
			 size[a]+=size[b];
		 }
	 }
	 
	 
	 
//*******************************************PRIME FACTORIZE *****************************************************************************************************//
	 static TreeMap<Long,Long> prime(long n)
	 {
		 TreeMap<Long,Long>h=new TreeMap<>();
		 long num=n;
		 
		 for(int i=2;i<=Math.sqrt(num);i++)
		 {
			 if(n%i==0)
			 {
				 int nt=0;
				 while(n%i==0) {
					 n=n/i;
					 nt++;
				 }
				 h.put((long)i, (long)nt);
			 }
		 }
		 if(n!=1)
			 h.put((long)n, (long)1);
		 return h;
		 
	 }
	 
///////////////////////****************************************-----------------------------.........................>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>***********************************************	
	 
	static long [] xsort(long A[])
	{
		ArrayList<Long>l=new ArrayList<>();
		for(long a:A)
			l.add(a);
		Collections.sort(l);
		for(int i=0;i<l.size();i++)
			A[i]=l.get(i);
		
			return A;
		
		
	}
	 
	
//*************CLASS PAIR ***********************************************************************************************************************************************
	static class pair implements Comparable<pair>
    {
        long x;
        long y;

        pair(long x, long y) 
        {
            this.x = x;
            this.y = y;
        }
        
        public int compareTo(pair o)
        {
        	return (int)(y-o.y);
        	
        }
		
       
    }
    
//*************CLASS PAIR *****************************************************************************************************************************************************
	
	
	

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int Int() {
            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;
        }

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

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return String();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void print(Object... objects) {
            for (int i = 0; i < objects.length; i++) {
                if (i != 0)
                    writer.print(' ');
                writer.print(objects[i]);
            }
        }

        public void printLine(Object... objects) {
            print(objects);
            writer.println();
        }

        public void close() {
            writer.close();
        }

        public void flush() {
            writer.flush();
        }
    }

    static InputReader in = new InputReader(System.in);
    static OutputWriter out = new OutputWriter(System.out);
    static int modulus = (int) 1e7;

    public static int[] sort(int[] a) {
        int n = a.length;
        ArrayList<Integer> l = new ArrayList<>();
        for (int i : a)
            l.add(i);
        Collections.sort(l);
        for (int i = 0; i < l.size(); i++)
            a[i] = l.get(i);
        return a;
    }

    public static long pow(long x, long y) {
        long res = 1;
        while (y > 0) {
            if (y % 2 != 0) {
                res = (res * x) % modulus;
                y--;

            }
            x = (x * x) % modulus;
            y = y / 2;
        }
        return res;
    }
//GCD___+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    public static long gcd(long x, long y) {
        if (x == 0)
            return y;
        else
            return gcd(y % x, x);
    }
    //****************LOWEST COMMON MULTIPLE   *************************************************************************************************************************************

    public static long lcm(long x, long y) {
        return (x * (y / gcd(x, y)));
    }
//INPUT PATTERN******************************************************************************************************************************************************************
    public static int i() {
        return in.Int();
    }

    public static long l() {
        String s = in.String();
        return Long.parseLong(s);
    }

    public static String s() {
        return in.String();
    }

    public static int[] readArray(int n) {
        int A[] = new int[n];
        for (int i = 0; i < n; i++) {
            A[i] = i();
        }
        return A;
    }

    public static long[] readArray(long n) {
        long A[] = new long[(int) n];
        for (int i = 0; i < n; i++) {
            A[i] = l();
        }
        return A;
    }

//////////////////////////************************************INVERSE MODULO******************************************************************
static class inverse 
{
	static int N;
	static long[] factorialNumInverse;
	static long[] naturalNumInverse;
	static long[] fact;
	inverse(int n)
	{
		this.N=n;
		
		 factorialNumInverse = new long[N + 1];
		 
	    // Array to precompute inverse of 1! to N!
	     naturalNumInverse = new long[N + 1];
	 
	    // Array to store factorial of first N numbers
	     fact = new long[N + 1];
	     
	 
	}
	

// Function to precompute inverse of numbers
static void InverseofNumber(int p)
{
naturalNumInverse[0] = naturalNumInverse[1] = 1;

for(int i = 2; i <= N; i++)
    naturalNumInverse[i] = naturalNumInverse[p % i] *
            (long)(p - p / i) % p;
}

// Function to precompute inverse of factorials
static void InverseofFactorial(int p)
{
factorialNumInverse[0] = factorialNumInverse[1] = 1;

// Precompute inverse of natural numbers
for(int i = 2; i <= N; i++)
    factorialNumInverse[i] = (naturalNumInverse[i] *
            factorialNumInverse[i - 1]) % p;
}

// Function to calculate factorial of 1 to N
static void factorial(int p)
{
fact[0] = 1;

// Precompute factorials
for(int i = 1; i <= N; i++)
{
    fact[i] = (fact[i - 1] * (long)i) % p;
}
}

// Function to return nCr % p in O(1) time
static long comb(int N, int R, int p)
{

// n C r = n!*inverse(r!)*inverse((n-r)!)
long ans = ((fact[N] * factorialNumInverse[R]) %
        p * factorialNumInverse[N - R]) % p;

return ans;
}
}
//////////////////////////************************************INVERSE MODULO******************************************************************
}