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:
//package Div_170;
//Xudo xoxlasa Accepted

import java.util.Scanner;

public class D {
public static void main(String[] args) {
	Scanner sc=new Scanner(System.in);
	int n=sc.nextInt();
	int m=sc.nextInt();
	if (n - m >= 2 && m < 4) {
		System.out.println(-1);
		return;
	}

	for (int i = 1; i <= m; i++) {
		System.out.println(String.format("%d %d", i, i * i));
	}
	for (int i = 1; i <= n - m; i++) {
		System.out.println(String.format("%d %d", 40001 + i * i, i));
	}
	
	}
}