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.BufferedOutputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.TreeSet;


public class C2 {

    public static void solve() throws Exception {
	int n = nextInt();
	int k = nextInt();
	List<Song> list = new ArrayList<>(n);
	
	for(int i=0;i<n;i++) {
	    Song s = new Song();
	    list.add(s);
	    s.t = nextInt();
	    s.b = nextInt();
	}
	Collections.sort(list);
	TreeSet<Song> tree = new TreeSet<>((a, b) -> {
	    int ret = -Integer.valueOf(a.t).compareTo(b.t);
	    if(ret == 0) {
		ret = Integer.valueOf(a.nr).compareTo(b.nr);
	    }
	    return ret;
	});
	long sum = 0;
	long max = 0;
	for(int i=0;i<n;i++) {
	    Song s = list.get(i);
	    tree.add(s);
	    sum += s.t;
	    if(tree.size() > k) {
		Song last = tree.last();
		sum -= last.t;
		tree.remove(last);
	    }
	    //if(tree.size() == k)
	    {
		long v = sum * s.b;
		if(v > max) {
		    max = v;
		}
	    }
	}
	println(max);
	
	
    }
    
    private static class Song implements Comparable<Song> {
	private static int cnt = 0;
	int nr = 0;
	int t;
	int b;
	
	public Song() {
	    this.nr = cnt++;
	}
	
	@Override
	public int compareTo(Song s) {
	    int ret = -new Integer(b).compareTo(s.b);
	    return ret;
	}
	
	@Override
	public String toString() {
	    return t + "," + b;
	}
    }
    


    public static void main(String[] args) throws Exception {
	try {
	    fastReader = new FastReader(System.in);
	    systemOut = new BufferedOutputStream(System.out);
	    solve();
	} finally {
	    systemOut.close();
	}
    }

    private static FastReader fastReader = null;
    private static BufferedOutputStream systemOut = null;

    public static void print(Object obj) {
	print(obj.toString());
    }

    public static void print(String str) {
	try {
	    systemOut.write(str.getBytes("utf-8"));
	} catch (Exception ex) {
	    throw new RuntimeException(ex);
	}
    }

    public static void println(Object obj) {
	println(obj.toString());
    }

    public static void println(String str) {
	try {
	    print(str);
	    systemOut.write('\n');
	} catch (Exception ex) {
	    throw new RuntimeException(ex);
	}
    }

    public static String next() {
	return fastReader.readNextToken(false);
    }

    public static String nextLine() {
	return fastReader.readNextToken(true);
    }

    public static int nextInt() {
	return Integer.parseInt(fastReader.readNextToken(false));
    }

    public static long nextLong() {
	return Long.parseLong(fastReader.readNextToken(false));
    }

    public static double nextDouble() {
	return Double.parseDouble(fastReader.readNextToken(false));
    }

    static class FastReader {
	private byte[] buf = new byte[65536];
	private int ind = 0;
	private int maxInd = -1;
	private InputStream is = null;
	private boolean eof = false;
	private boolean lastCharRead = false;

	public FastReader(InputStream is) {
	    this.is = is;
	}

	public String readNextToken(boolean endOfLine) {
	    try {
		StringBuilder sb = new StringBuilder();
		boolean found = false;
		while (true) {
		    if (lastCharRead) {
			return null;
		    } else if (ind > maxInd) {
			if (eof) {
			    lastCharRead = true;
			} else {
			    fillBuffer();
			}
		    }
		    byte b = '\n';
		    if (!lastCharRead) {
			b = buf[ind++];
		    }

		    if (b == '\r') {
			// ignore
		    } else if ((b == '\n' && endOfLine) || (Character.isWhitespace(b) && !endOfLine)) {
			if (found) {
			    break;
			}
		    } else {
			sb.append((char) b);
			found = true;
		    }
		}
		return sb.toString();
	    } catch (Exception ex) {
		throw new RuntimeException(ex);
	    }
	}

	private void fillBuffer() {
	    try {
		int read = is.read(buf, 0, buf.length);
		if (read < buf.length) {
		    eof = true;
		}
		ind = 0;
		maxInd = read - 1;
	    } catch (Exception ex) {
		throw new RuntimeException(ex);
	    }
	}
    }
}