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.
import java.util.*;
import java.io.*;
//import java.lang.*;

public class ranjan{

    //public static Read cin;
    public static InputReader cin;
    public static PrintWriter cout;
    public static boolean[] visited;
    public static int node=-1;
    public static boolean flag;
    public static final long b = (long)1e9+7;
    public static int fileread = 0; 
    
    public static void main(String ...arg) throws IOException
    {
        /*console writer*/
        cout = new PrintWriter(new BufferedOutputStream(System.out));
        /*Debug Reader*/
        //Scan cin =new Scan();
        if(fileread == 1)
        {
            try
            {
            //cin = new Read(new FileInputStream(new File("in1.txt")));
            cin = new InputReader(new FileInputStream(new File("in1.txt")));
            }
            catch (IOException error){}
        }
        else{
            //cin = new Read(System.in);
            cin = new InputReader(System.in);
        }

        int n = cin.nextInt();
        int k = cin.nextInt();
        
        Song[] arr = new Song[n];
        for(int i = 0;i<n;i++)
        {
            arr[i] = new Song(cin.nextInt(),cin.nextInt());
        }
           
        Arrays.sort(arr,new Comparator<Song>(){
            public int compare(Song a,Song b)
            {
                return b.beauty - a.beauty;
            }
        });

        PriorityQueue<Integer> pq = new PriorityQueue<>();
        long sum = 0,ans = 0;
        for(int i=0;i<n;i++)
        {
            sum += arr[i].length;
            pq.add(arr[i].length);
            while(pq.size() > k)
                sum -= pq.remove();
            ans = Math.max(ans,sum * (arr[i].beauty));
        }

        cout.print(ans);
        cout.close();
    }

    static class Song{
        public int length;
        public int beauty;
        
        public Song(int a,int b)
        {
            this.length = a;
            this.beauty = b;   
        }
    }

    public static <K, V> V getOrDefault(HashMap<K,V> map, K key, V defaultValue) {
        return map.containsKey(key) ? map.get(key) : defaultValue;
    }
    

    public static long mod_pow(long x,long n,long mod) {
		long res=1;
		while(n>0) {
			if((n&1)==1)res=res*x%mod;
			x=x*x%mod;
			n>>=1;
		}
		return res;
    }
    public static int gcd(int n1, int n2) 
	{
		int r;
		while (n2 != 0) 
		{
			r = n1 % n2;
			n1 = n2;
			n2 = r;
		}
		return n1;
	}
 
	/*public static long lcm(long n1, long n2) 
	{
		long answer = (n1 * n2) / (gcd(n1, n2));
		return answer;
	}*/


    static class InputReader {
        final InputStream is;
        final byte[] buf = new byte[1024];
        int pos;
        int size;
 
        public InputReader(InputStream is) {
            this.is = is;
        }
 
        public int nextInt() {
            int c = read();
            while (isWhitespace(c))
                c = read();
            int sign = 1;
            if (c == '-') {
                sign = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res = res * 10 + c - '0';
                c = read();
            } while (!isWhitespace(c));
            return res * sign;
        }
 
        int read() {
            if (size == -1)
                throw new InputMismatchException();
            if (pos >= size) {
                pos = 0;
                try {
                    size = is.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (size <= 0)
                    return -1;
            }
            return buf[pos++] & 255;
        }
 
        static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
 
    }

static class RecursionLimiter {
    public static long maxLevel = 1549;

    public static void emerge() {
        if (maxLevel == 0)
            return;
        try {
            throw new IllegalStateException("Too deep, emerging");
        } catch (IllegalStateException e) {
            if (e.getStackTrace().length > maxLevel + 1)
                throw e;
        }
    }
}


static class Scan {
        private byte[] buf=new byte[1024];
        private int index;
        private InputStream in;
        private int total;
        public Scan()
        {
            in=System.in;
        }
        public int scan()throws IOException
        {
            if(total<0)
            throw new InputMismatchException();
            if(index>=total)
            {
                index=0;
                total=in.read(buf);
                if(total<=0)
                return -1;
            }
            return buf[index++];
        }
        public int scanInt()throws IOException
        {
            int integer=0;
            int n=scan();
            while(isWhiteSpace(n))
            n=scan();
            int neg=1;
            if(n=='-')
            {
                neg=-1;
                n=scan();
            }
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    integer*=10;
                    integer+=n-'0';
                    n=scan();
                }
                else throw new InputMismatchException();
            }
            return neg*integer;
        }
        public double scanDouble()throws IOException
        {
            double doub=0;
            int n=scan();
            while(isWhiteSpace(n))
            n=scan();
            int neg=1;
            if(n=='-')
            {
                neg=-1;
                n=scan();
            }
            while(!isWhiteSpace(n)&&n!='.')
            {
                if(n>='0'&&n<='9')
                {
                    doub*=10;
                    doub+=n-'0';
                    n=scan();
                }
                else throw new InputMismatchException();
            }
            if(n=='.')
            {
                n=scan();
                double temp=1;
                while(!isWhiteSpace(n))
                {
                    if(n>='0'&&n<='9')
                    {
                        temp/=10;
                        doub+=(n-'0')*temp;
                        n=scan();
                    }
                    else throw new InputMismatchException();
                }
            }
            return doub*neg;
        }
        public String scanString()throws IOException
        {
            StringBuilder sb=new StringBuilder();
            int n=scan();
            while(isWhiteSpace(n))
            n=scan();
            while(!isWhiteSpace(n))
            {
                sb.append((char)n);
                n=scan();
            }
            return sb.toString();
        }
        private boolean isWhiteSpace(int n)
        {
            if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
            return true;
            return false;
        }
    }

}

class Read
{
    private BufferedReader br;
    private StringTokenizer st;

    public Read(InputStream is)
    { br = new BufferedReader(new InputStreamReader(is)); }

    String next()
    {
        while (st == null || !st.hasMoreElements())
        {
            try {st = new StringTokenizer(br.readLine());}
            catch(IOException e)
                {e.printStackTrace();}
        }
        return st.nextToken();
    }

    int nextInt()
    { return Integer.parseInt(next()); }

    long nextLong()
    { return Long.parseLong(next()); }

    double nextDouble()
    { return Double.parseDouble(next()); }

    String nextLine()
    {
        String str = "";
        try {str = br.readLine();}
        catch(IOException e)
            {e.printStackTrace();}
        return str;
    }
}


