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.io.*;
import java.util.*;

public class Solu {
    static StringBuffer str = new StringBuffer();
    static InputReader in = new InputReader(System.in);
    static int mm = 1000000007;
    static int n;
    static ArrayList<Integer> tree[];
    static boolean vis[];
    static long dp[][];
    static long time[];
    static long beu[];
    public static void main(String[] args) {
        int t, i, j, tt, m, k;
        t = 1;
        for (tt = 0; tt < t; tt++) {
            n=in.nextInt();
            k=in.nextInt();
            Entity[] en=new Entity[n];
            for(i=0;i<n;i++){
                int l=in.nextInt();
                int r=in.nextInt();
                en[i]=new Entity(r,l);
            }
            Arrays.sort(en,com);
            long maxs[]=new long[n];
            PriorityQueue<Integer> pq=new PriorityQueue<>();
            long sum=0;
            int cc=1;
            int last=en[n-1].c;
            for(i=n-2;i>=0;i--){
                if(cc==k){
                    if(pq.size()==0)
                        continue;
                    if(pq.peek()>=last){
                        maxs[i]=sum;
                    }else{
                        sum-=pq.peek();
                        pq.poll();
                        sum+=last;
                        maxs[i] = sum;
                        pq.add(last);
                    }
                }else{
                    pq.add(last);
                    sum+=last;
                    maxs[i] = sum;
                    cc++;
                }
                last=en[i].c;
            }
            long ans = 0;
            for (i = 0; i < n; i++) {
                long gh = (long)en[i].a*(maxs[i] +en[i].c);
                ans=Math.max(gh,ans);
            }
            ap(ans+"\n");
        }

        pn();
    }

    static void initT(int n) {
        vis = new boolean[n];
        tree = new ArrayList[n];
        for (int i = 0; i < n; i++) {
            tree[i] = new ArrayList<>();
        }
    }

    static class hog {

        char ch;
    }

    static final Comparator<Entity> com = new Comparator<Entity>() {
        public int compare(Entity x, Entity y) {
            int xx = Integer.compare(x.a, y.a);
            if (xx == 0) {
                return Long.compare(y.c, x.c);
            } else {
                return xx;
            }
        }
    };

    static class Pair {

        int a, b, c;

        Pair(int x, int y, int z) {
            a = x;
            b = y;
            c = z;
        }
    }

    static class Entity {

        int a;
        int c;

        Entity(int p, int q) {
            a = p;
            c = q;
        }
    }

    static long gcd(long a, long b) {
        return (b == 0) ? a : gcd(b, a % b);
    }

    static int gcdi(int a, int b) {
        return (b == 0) ? a : gcdi(b, a % b);
    }

    static long power(long x, int y, int m) {
        if (y == 0) {
            return 1;
        }
        long p = power(x, y / 2, m) % m;
        p = (p * p) % m;
        return (y % 2 == 0) ? p : (x * p) % m;
    }

    public static void ap(String st) {
        str.append(st);
    }

    public static void pn() {
        System.out.println(str);
    }

    static class InputReader {

        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

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

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

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

        public void skip(int x) {
            while (x-- > 0) {
                read();
            }
        }

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

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

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

        public String next() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuffer res = new StringBuffer();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));

            return res.toString();
        }

        public String nextLine() {
            StringBuffer buf = new StringBuffer();
            int c = read();
            while (c != '\n' && c != -1) {
                if (c != '\r') {
                    buf.appendCodePoint(c);
                }
                c = read();
            }
            return buf.toString();
        }


        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E') {
                    return res * Math.pow(10, nextInt());
                }
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E') {
                        return res * Math.pow(10, nextInt());
                    }
                    if (c < '0' || c > '9') {
                        throw new InputMismatchException();
                    }
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public boolean hasNext() {
            int value;
            while (isSpaceChar(value = peek()) && value != -1) {
                read();
            }
            return value != -1;
        }

        private boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
    }
}
