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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
import java.util.function.Function;

public class Main {

    public static void main(String[] args) {

        Parser parser = new Parser();
        int t = 1;
        for (int i = 1; i <= t; i++) {
            Problem problem = new Problem();
            problem.solve(i);
        }
    }
}

class Problem {
    Parser parser = new Parser();

    public void solve(int testNum) {
        int n = parser.parseInt();
        int k = parser.parseInt();

        List<Pair> pairs = new ArrayList<>();
        for(int i = 0; i < n; i++) {
            pairs.add(new Pair(parser.parseInt(), parser.parseInt()));
        }

        pairs.sort(Comparator.comparing(Pair::getB, Comparator.reverseOrder())
        .thenComparing(Pair::getT, Comparator.reverseOrder()));

        long ans = 0;
        long sum = 0;
        PriorityQueue<Integer> priorityQueue = new PriorityQueue<>();
        for(int i = 0; i < k; i++) {
            Pair pair = pairs.get(i);
            priorityQueue.add(pair.t);
            sum += pair.t;
            ans = Math.max(ans, sum * pair.b);
        }

        for(int i = k; i < n; i++) {
            Pair pair = pairs.get(i);
            sum -= priorityQueue.poll();
            sum += pair.t;
            priorityQueue.add(pair.t);
            ans = Math.max(ans, sum * pair.b);
        }
        System.out.println(ans);
    }

    static class Pair {
        int t, b;

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

        public int getT() {
            return t;
        }

        public int getB() {
            return b;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Pair pair = (Pair) o;
            return t == pair.t &&
                    b == pair.b;
        }

        @Override
        public int hashCode() {
            return Objects.hash(t, b);
        }

        @Override
        public String toString() {
            return "Pair{" +
                    "t=" + t +
                    ", b=" + b +
                    '}';
        }
    }
}

class MathUtil {

    public static List<Integer> getPrimes(int r) {
        if (r < 2) {
            return List.of();
        }

        List<Integer> result = new ArrayList<>();
        result.add(2);
        boolean[] is = new boolean[r + 1];
        for (int i = 4; i <= r; i += 2) {
            is[i] = true;
        }
        for (int i = 3; i <= r; i += 2) {
            if (is[i]) continue;
            result.add(i);
            for (long j = (long) i * i; j <= r; j += i) {
                is[(int) j] = true;
            }
        }
        return result;
    }

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

    public static long pow(long x, long y) {
        return pow(x, y, Function.identity());
    }

    public static long pow(long x, long y, long mod) {
        return pow(x, y, v -> v % mod);
    }

    private static long pow(long x, long y, Function<Long, Long> action) {
        long res = 1;
        long t = x;
        while (y > 0) {
            if ((y & 1) == 1) {
                res += t;
                res = action.apply(res);
            }
            t *= t;
            t = action.apply(t);
            y /= 2;
        }
        return res;
    }
}

class DisjointSet {

    private final int[] f;

    public DisjointSet(int size) {
        f = new int[size + 1];
        for (int i = 0; i <= size; i++) {
            f[i] = i;
        }
    }

    public int find(int u) {
        if (f[u] == u) return u;
        return f[u] = find(f[u]);
    }

    public boolean merge(int u, int v) {
        u = find(u);
        v = find(v);
        if (u == v) return false;
        if (u > v) {
            int t = u;
            u = v;
            v = t;
        }
        f[u] = v;
        return true;
    }
}

class Parser {
    private static final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    private StringTokenizer tokenizer;

    public int parseInt() {
        fill();
        return Integer.parseInt(tokenizer.nextToken());
    }

    public long parseLong() {
        fill();
        return Long.parseLong(tokenizer.nextToken());
    }

    public double parseDouble() {
        fill();
        return Double.parseDouble(tokenizer.nextToken());
    }

    public String parseLine() {
        try {
            return reader.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    String parseString() {
        fill();
        return tokenizer.nextToken();
    }

    private void fill() {
        while (tokenizer == null || !tokenizer.hasMoreElements()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}