Problem: Convexity of a set of points on the plane is the size of the largest subset of points that form a convex polygon. Your task is to build a set of n points with the convexity of exactly m. Your set of points should not contain three points that lie on a straight line.

Input

The single line contains two integers n and m (3 ≤ m ≤ 100, m ≤ n ≤ 2m).

Output

If there is no solution, print "-1". Otherwise, print n pairs of integers — the coordinates of points of any set with the convexity of m. The coordinates shouldn't exceed 108 in their absolute value.

Examples

Input

4 3


Output

0 0
3 0
0 3
1 1


Input

6 3


Output

-1


Input

6 6


Output

10 0
-10 0
10 1
9 1
9 -1
0 -2


Input

7 4


Output

176166 6377
709276 539564
654734 174109
910147 434207
790497 366519
606663 21061
859328 886001

Solution (in JAVA):

Solution:
import java.util.*;

public class SetOfPoints {
	public static void main(String[] args) {
		Scanner cin = new Scanner(System.in);
		int n = cin.nextInt();
		int m = cin.nextInt();
		if (m == 3) {
			switch (n) {
			case 3:
				System.out.println("0 0");
				System.out.println("1 0");
				System.out.println("0 1");
				System.exit(0);
			case 4:
				System.out.println("0 0");
				System.out.println("0 3");
				System.out.println("3 0");
				System.out.println("1 1");
				System.exit(0);
			default:
				System.out.println("-1");
				System.exit(0);
			}
		}
		for (int i = 1; i <= n - m; i++) {
			System.out.println(i + " " + (10000000 + i * i));
		}
		for (int i = 1; i <= m; i++) {
			System.out.println(i + " " + (-10000000 - i * i));
		}
		cin.close();
	}
}