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.
//package com.company;
// Always comment out package when submitting.

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

public class Main {
    public static class Task {

        public class Song {
            int t, b, idx;

            public Song(int t, int b, int idx) {
                this.t = t;
                this.b = b;
                this.idx = idx;
            }
        }

        public void solve(Scanner sc, PrintWriter pw) throws IOException {
            int n = sc.nextInt();
            int k = sc.nextInt();
            int[][] songs = new int[n][2];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < 2; j++) {
                    songs[i][j] = sc.nextInt();
                }
            }
            Arrays.sort(songs, new Comparator<int[]>() {
                @Override
                public int compare(int[] o1, int[] o2) {
                    return Integer.compare(o1[1], o2[1]);
                }
            });
            PriorityQueue<Song> pq = new PriorityQueue<>(new Comparator<Song>() {
                @Override
                public int compare(Song o1, Song o2) {
                    if (o1.t == o2.t) {
                        return o2.b - o1.b;
                    }
                    return o2.t - o1.t;
                }
            });
            for (int i = 0; i < n; i++) {
                pq.add(new Song(songs[i][0], songs[i][1], i));
            }
            boolean[] validIdx = new boolean[n];
            boolean[] isIdx = new boolean[n];
            long tot = 0;
            for (int i = 0; i < k; i++) {
                Song s = pq.poll();
                tot += s.t;
                isIdx[s.idx] = true;

            }
            long best = 0;
            for (int i = 0; i < n; i++) {
                best = Math.max(best, tot * songs[i][1]);
                validIdx[i] = true;
                if (isIdx[i]) {
                    isIdx[i] = false;
                    tot -= songs[i][0];
                    while (pq.size() > 0 && validIdx[pq.peek().idx]) pq.poll();
                    if (pq.size() > 0) {
                        Song s = pq.poll();
                        isIdx[s.idx] = true;
                        tot += s.t;
                    }
                }
            }
            pw.println(best);
        }
    }

    // template, actual code is in class Task.
    static long TIME_START, TIME_END;

    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
//        Scanner sc = new Scanner(new FileInputStream("Test.in"));
        PrintWriter pw = new PrintWriter(new BufferedOutputStream(System.out));
//        PrintWriter pw = new PrintWriter(new FileOutputStream("Test.out"));
        Runtime runtime = Runtime.getRuntime();
        long usedMemoryBefore = runtime.totalMemory() - runtime.freeMemory();
        TIME_START = System.currentTimeMillis();
        Task t = new Task();
        t.solve(sc, pw);
        TIME_END = System.currentTimeMillis();
        long usedMemoryAfter = runtime.totalMemory() - runtime.freeMemory();
        pw.close();
//        System.err.println("Memory increased: " + (usedMemoryAfter - usedMemoryBefore) / 1000000);
//        System.err.println("Time used: " + (TIME_END - TIME_START) + ".");
    }

    // Faster IO with BufferedReader wrapped with Scanner
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(FileReader s) throws FileNotFoundException {
            br = new BufferedReader(s);
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

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

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

        public String nextLine() throws IOException {
            return br.readLine();
        }

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

        public boolean ready() throws IOException {
            return br.ready();
        }
    }
}