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.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Solution {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());

		int n = Integer.parseInt(st.nextToken());
		int k = Integer.parseInt(st.nextToken());

		Point[] points = new Point[n];
		for (int i = 0; i < n; i++) {
			st = new StringTokenizer(br.readLine());
			int t = Integer.parseInt(st.nextToken());
			int b = Integer.parseInt(st.nextToken());
			points[i] = new Point(t, b);
		}
		Arrays.sort(points);

		Heap h = new Heap(k);
		long[] sum = new long[n];

		for (int i = 0; i < k - 1; i++) {
			sum[n - 1 - i] = h.getSum();
			h.add(points[n - 1 - i].t);
		}

		for (int i = n - k; i >= 0; i--) {
			sum[i] = h.getSum();
			h.replaceWithMin(points[i].t);
		}

		long max = -1l;
		for (int i = 0; i < n; i++) {
			max = Math.max(max, (sum[i] + points[i].t) * points[i].b);
		}

		System.out.println(max);

	}
}

class Point implements Comparable<Point> {
	int t, b;

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

	@Override
	public int compareTo(Point o) {
		return this.b - o.b;
	}

	@Override
	public String toString() {
		return "Point [t=" + t + ", b=" + b + "]";
	}

}

class Heap {
	int size;
	int[] a;
	long sum = 0;

	Heap(int n) {
		size = 0;
		a = new int[n + 1];
	}

	public long getSum() {
		return sum;
	}

	void add(int t) {
		sum += t;
		int in = ++size;
		a[in] = t;

		while (in > 0) {
			int par = in / 2;
			if (a[par] > a[in]) {
				int temp = a[in];
				a[in] = a[par];
				a[par] = temp;
			}
			in = par;
		}
	}

	int getMin() {
		return a[1];
	}

	long replaceWithMin(int t) {

		if (t <= a[1]) {
			return sum;
		}
		int in = 1;
		if (in <= size) {
			sum = sum - a[1] + t;
			a[1] = t;
		}

		while (in <= size) {
			int left = 2 * in;
			int right = 2 * in + 1;

			if (left <= size) {
				if (right <= size) {

					if (a[left] <= a[right]) {
						if (a[in] > a[left]) {
							int temp = a[left];
							a[left] = a[in];
							a[in] = temp;
							in = left;
							continue;
						} else {
							return sum;
						}
					} else {
						if (a[in] > a[right]) {
							int temp = a[right];
							a[right] = a[in];
							a[in] = temp;
							in = right;
							continue;
						} else {
							return sum;
						}
					}
				} else {

					if (a[in] > a[left]) {
						int temp = a[left];
						a[left] = a[in];
						a[in] = temp;
						in = left;
					} else {
						return sum;
					}
				}
			} else {
				return sum;
			}
		}
		return sum;
	}
}