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 B277 {
public static void main(String[] args)
{
    Scanner input = new Scanner(System.in);
    int n = input.nextInt(), m = input.nextInt();
    if(n <= 4 && m == 3)
    {
        System.out.println("0 0");
        System.out.println("0 3");
        System.out.println("3 0");
        if(n == 4) System.out.println("1 1");
    }
    else if(m == 3) System.out.println(-1);
    else
    {
        for(int i = 0; i<m; i++)
        {
            System.out.println(i+" "+i*i);
        }
        for(int i = 0; i<n-m; i++)
        {
            System.out.println((i+n)+" "+-(n+m-i)*(n+m-i));
        }
    }
}
}