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.Scanner;


public class CodeforcesRound170C {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        
        Scanner kde = new Scanner(System.in);
        int n= kde.nextInt();       
        int m=kde.nextInt(); 
            
        
        if(m == 3){
            if(n == 3){
              System.out.println("0 0");
              System.out.println("0 1");
              System.out.println("1 0");
              return;
            }
            
            if(n == 4){
        
                  System.out.println("0 3");
                  System.out.println("0 0");
                  System.out.println("3 0");
                  System.out.println("1 1");
                return ;
            }
            if(n >= 5){
                  System.out.println("-1");
                return;
            }
        }
        
            
        
        


        
        int X = 10000000;
        for(int i=0; i <m; i++ )
        {
            System.out.println(i+" "+(X+i*i));
        }
        for(int i=0; i <n-m; i++ )
        {
            System.out.println(i+" "+(-X-i*i));
        }
        
        
       


    }

}