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

public class Edu62C {
    private static boolean debug = false;

    private static int N, K;
    private static Song[] A;


    private static void solveProblem(InputStream instr) throws Exception {
        InputReader sc = new InputReader(instr);
        int testCount = 1;
        if (debug) {
            testCount = sc.nextInt();
        }

        for (int t = 1; t <= testCount; t++) {
            printDebug("------ " + t + " ------");
            N = sc.nextInt();
            K = sc.nextInt();
            A = new Song[N];
            for(int i = 0; i < N; i++){
                A[i] = new Song(sc.nextInt(), sc.nextInt());
            }
            Object result = solveTestCase();
            System.out.println(result);
        }
    }

    private static Object solveTestCase() {
        Arrays.sort(A, new Comparator<Song>() {
            @Override
            public int compare(Song o1, Song o2) {
                return o2.beauty - o1.beauty;
            }
        });
        long max = 0;
        long sum = 0;
        PriorityQueue<Integer> selected = new PriorityQueue<>();
        for(Song s: A){
            selected.add(s.len);
            sum += s.len;
            while(selected.size() > K) {
                Integer first = selected.poll();
                sum -= first;
            }
            //  System.out.println(s.beauty + "\t" + sum);
            max = Math.max(max, s.beauty * sum);
        }
        return max;
    }

    private static class Song {
        int len, beauty;
        Song(int len, int beauty){
            this.len = len;
            this.beauty = beauty;
        }
    }

    private static int[] readInts(InputReader sc, int N) throws Exception {
        int[] arr = new int[N];
        for (int i = 0; i < N; i++) {
            arr[i] = sc.nextInt();
        }
        return arr;
    }

    private static String joinValues(List<? extends Object> list, String delim) {
        return list.stream().map(Object::toString).collect(Collectors.joining(delim));
    }

    private static String joinValues(int[] arr, String delim) {
        List<Object> list = new ArrayList<>();
        for (Object value : arr) {
            list.add(value);
        }
        return list.stream().map(Object::toString).collect(Collectors.joining(delim));
    }

    public static void printDebug(Object str) {
        if (debug) {
            System.out.println("DEBUG: " + str);
        }
    }


    private static void printOut(String out) {
        System.out.println(out);
    }

    public static String printArr(int[] arr) {
        StringBuilder builder = new StringBuilder();
        for (int in : arr) {
            builder.append(in).append(" ");
        }
        return builder.toString();
    }

    private static final class InputReader {
        private final InputStream stream;
        private final byte[] buf = new byte[1024];
        private int curChar;
        private int Chars;

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

        private int read() throws Exception {
            if (curChar >= Chars) {
                curChar = 0;
                Chars = stream.read(buf);
                if (Chars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public final int nextInt() throws Exception {
            return (int)nextLong();
        }

        public final long nextLong() throws Exception {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
                if (c == -1)
                    throw new IOException();
            }
            boolean negative = false;
            if (c == '-') {
                negative = true;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += (c - '0');
                c = read();
            } while (!isSpaceChar(c));
            return negative ? (-res) : (res);
        }

        public final int[] nextIntBrray(int size) throws Exception {
            int[] arr = new int[size];
            for (int i = 0; i < size; i++)
                arr[i] = nextInt();
            return arr;
        }

        public final String next() throws Exception {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.append((char)c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public final String nextLine() throws Exception {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.append((char)c);
                c = read();
            } while (c != '\n' && c != -1);
            return res.toString();
        }

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

    public static void main(String[] args) throws Exception {
        long currTime = System.currentTimeMillis();
        try {
            if (new File("input.in").exists()) {
                debug = true;
            }
        } catch (Throwable ex) {

        }
        if (debug) {
            solveProblem(new FileInputStream(new File("input.in")));
            System.out.println("Time: " + (System.currentTimeMillis() - currTime));
        } else {
            solveProblem(System.in);
        }
    }

}