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 javax.swing.text.InternationalFormatter;

import java.math.*;

public class template {

	static long time = 0, mp = Integer.MAX_VALUE, k = 0, cnt = 0, edge = 0, no = 0;

	static boolean bul = false;
	static int[] ht;
	static long[] dis;
	static boolean[][] b;
	static char[][] g;
	static String sb = "";
	static ArrayList<Integer>[] a;
	static HashSet<Long>[] c;
	public static PrintWriter out;

	static HashMap<Integer, HashSet<Integer>> hm = new HashMap<>();

	static ArrayList<Long> p = new ArrayList<>();

	public static void main(String[] args) throws IOException {

		Reader scn = new Reader();

		int n = scn.nextInt(), k = scn.nextInt();

		PriorityQueue<pair> pq = new PriorityQueue<>();

		ArrayList<pair> p = new ArrayList<>();

		for (int i = 0; i < n; i++) {
			p.add(new pair(scn.nextInt(), scn.nextInt()));
		}

		Collections.sort(p, new comp());

		// for(pair t:p)
		// System.out.println(t.t+" "+t.b);
		//

		long ans = Integer.MIN_VALUE, ktime=0;
		
		for (int i = 0; i < p.size(); i++) {


			long beaudy = p.get(i).b;
			long time = p.get(i).t;

			ans = Math.max(ans, (long)(beaudy * (time + ktime)));
			
			 if(pq.size() < k-1){
				 pq.add(p.get(i));
				 ktime+=p.get(i).t;
			 }
			 
			 else{
				     if(pq.size()!=0 && pq.peek().t <p.get(i).t){
				    	 ktime-=pq.remove().t;
				    	 ktime+=p.get(i).t;
				    	 pq.add(p.get(i));
				     }
			 }

		}

		System.out.println(ans);
	}

	// _________________________TEMPLATE_____________________________________________________________

	static class comp implements Comparator<pair> {

		@Override
		public int compare(pair o1, pair o2) {
			return o2.b - o1.b;
		}

	}

	static class pair implements Comparable<pair> {
		int t;
		int b;
		int d;

		pair(int a, int b) {
			this.t = a;
			this.b = b;
			this.d = a - b;
		}

		@Override
		public int compareTo(pair o) {

			return (int) (this.t - o.t);

		}
	}

	public static class Reader {
		final private int BUFFER_SIZE = 1 << 16;
		private DataInputStream din;
		private byte[] buffer;
		private int bufferPointer, bytesRead;

		public Reader() {
			din = new DataInputStream(System.in);
			buffer = new byte[BUFFER_SIZE];
			bufferPointer = bytesRead = 0;
		}

		public Reader(String file_name) throws IOException {
			din = new DataInputStream(new FileInputStream(file_name));
			buffer = new byte[BUFFER_SIZE];
			bufferPointer = bytesRead = 0;
		}

		public String readLine() throws IOException {
			byte[] buf = new byte[100000 + 1]; // line length
			int cnt = 0, c;
			while ((c = read()) != -1) {
				if (c == '\n')
					break;
				buf[cnt++] = (byte) c;
			}
			return new String(buf, 0, cnt);
		}

		public int nextInt() throws IOException {
			int ret = 0;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');

			if (neg)
				return -ret;
			return ret;
		}

		public long nextLong() throws IOException {
			long ret = 0;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');
			if (neg)
				return -ret;
			return ret;
		}

		public double nextDouble() throws IOException {
			double ret = 0, div = 1;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();

			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');

			if (c == '.') {
				while ((c = read()) >= '0' && c <= '9') {
					ret += (c - '0') / (div *= 10);
				}
			}

			if (neg)
				return -ret;
			return ret;
		}

		private void fillBuffer() throws IOException {
			bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
			if (bytesRead == -1)
				buffer[0] = -1;
		}

		private byte read() throws IOException {
			if (bufferPointer == bytesRead)
				fillBuffer();
			return buffer[bufferPointer++];
		}

		public void close() throws IOException {
			if (din == null)
				return;
			din.close();
		}

		public int[] nextIntArray(int n) throws IOException {
			int[] arr = new int[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextInt();
			}
			return arr;
		}

		public long[] nextLongArray(int n) throws IOException {
			long[] arr = new long[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLong();
			}
			return arr;
		}

		public int[][] nextInt2DArray(int m, int n) throws IOException {
			int[][] arr = new int[m][n];
			for (int i = 0; i < m; i++) {
				for (int j = 0; j < n; j++)
					arr[i][j] = nextInt();
			}
			return arr;
		}

	}

}