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

public class Main
{
    static class Node{
        int t,b;
        public Node(int t,int b){
            this.t=t;
            this.b=b;
        }
    }

    static class sortByBeaut implements Comparator<Node>{
        public int compare(Node A,Node B){
            if(A.b!=B.b)
                return A.b-B.b;
            return -(A.t-B.t);
        }
    }

    static long sum;

    public static void process()throws IOException
    {
        sum=0l;
        TreeSet<Integer> set = new TreeSet<Integer>();
        set.add(Integer.MAX_VALUE);
        HashMap<Integer, Integer> map = new HashMap<>();

        int n=ni(),k=ni();
        Node arr[]=new Node[n];

        for(int i=0;i<n;i++) arr[i]=new Node(ni(),ni());

        Arrays.sort(arr,new sortByBeaut());

        long suff[]=new long[n+1];

        int idx=n-1;
        for(int i=0;i<k-1;i++){
            //take[i]=arr[idx].b;
            sum+=(arr[idx].t)*1l;
            suff[idx]=sum;
            set.add(arr[idx].t);
            if(!map.containsKey(arr[idx].t))
                map.put(arr[idx].t,0);
            map.put(arr[idx].t,1+map.get(arr[idx].t));
            idx--;
        }

        for(int i=n-k;i>=0;i--){
            long curr=sum+(arr[i].t)*1l;

            suff[i]=curr;

            int l=set.first(),r=set.last();

            int present=arr[i].t;

            if(l<present){
                sum-=l*1l;
                sum+=present*1l;
                set.add(present);
                map.put(l,map.get(l)-1);
                if(map.get(l)==0){
                    map.remove(l);
                    set.remove(l);
                }
                if(!map.containsKey(present))
                    map.put(present,0);
                map.put(present,map.get(present)+1);
            }
        }
        //System.out.println(Arrays.toString(suff));
        long res=0l;
        for(int i=0;i<n;i++) res=Math.max(res, suff[i]*1l*(arr[i].b));
        pn(res);
    }


    static AnotherReader sc;
    static PrintWriter out;
    public static void main(String[]args)throws IOException
    {
        out = new PrintWriter(System.out);
        sc=new AnotherReader();
        boolean oj = true;

        oj = System.getProperty("ONLINE_JUDGE") != null;
        if(!oj) sc=new AnotherReader(100);

        long s = System.currentTimeMillis();
        int t=1;
        //t=ni();
        while(t-->0)
            process();
        out.flush();
        if(!oj)
            System.out.println(System.currentTimeMillis()-s+"ms");
        System.out.close();  
    }
    
    
    static void pn(Object o){out.println(o);}
    static void p(Object o){out.print(o);}
    static void pni(Object o){out.println(o);System.out.flush();}
    static int ni()throws IOException{return sc.nextInt();}
    static long nl()throws IOException{return sc.nextLong();}
    static double nd()throws IOException{return sc.nextDouble();}
    static String nln()throws IOException{return sc.nextLine();}
    static long gcd(long a, long b)throws IOException{return (b==0)?a:gcd(b,a%b);}
    static int gcd(int a, int b)throws IOException{return (b==0)?a:gcd(b,a%b);}
    static int bit(long n)throws IOException{return (n==0)?0:(1+bit(n&(n-1)));}
    static boolean multipleTC=false;
    static long mod=(long)1e9+7l;

    static void r_sort(int arr[],int n){
        Random r = new Random(); 
        for (int i = n-1; i > 0; i--){ 
            int j = r.nextInt(i+1); 
                  
            int temp = arr[i]; 
            arr[i] = arr[j]; 
            arr[j] = temp; 
        } 
        Arrays.sort(arr); 
    }

    static long mpow(long x, long n) {
        if(n == 0)
            return 1;
        if(n % 2 == 0) {
            long root = mpow(x, n / 2);
            return root * root % mod;
        }else {
            return x * mpow(x, n - 1) % mod;
        }
    }
    
    static long mcomb(long a, long b) {
        if(b > a - b)
            return mcomb(a, a - b);
        long m = 1;
        long d = 1;
        long i;
        for(i = 0; i < b; i++) {
            m *= (a - i);
            m %= mod;
            d *= (i + 1);
            d %= mod;
        }
        long ans = m * mpow(d, mod - 2) % mod;
        return ans;
    }
/////////////////////////////////////////////////////////////////////////////////////////////////////////

    static class AnotherReader{BufferedReader br; StringTokenizer st;
    AnotherReader()throws FileNotFoundException{
    br=new BufferedReader(new InputStreamReader(System.in));}
    AnotherReader(int a)throws FileNotFoundException{
    br = new BufferedReader(new FileReader("input.txt"));}
    String next()throws IOException{
    while (st == null || !st.hasMoreElements()) {try{
    st = new StringTokenizer(br.readLine());}
    catch (IOException  e){ e.printStackTrace(); }}
    return st.nextToken(); } int nextInt() throws IOException{
    return Integer.parseInt(next());}
    long nextLong() throws IOException
    {return Long.parseLong(next());}
    double nextDouble()throws IOException { return Double.parseDouble(next()); }
    String nextLine() throws IOException{ String str = ""; try{
    str = br.readLine();} catch (IOException e){
    e.printStackTrace();} return str;}}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////
}