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.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Scanner;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author pttrung
 */
public class D {

    public static void main(String[] args) {
        Scanner in = new Scanner(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        int n = in.nextInt();
        int m = in.nextInt();
        if (m == 3) {
            if (n >= 5) {
                out.println(-1);
            } else {
                out.println(0 + " " + 0);
                out.println(3 + " " + 0);
                out.println(0 + " " + 3);
                if (n == 4) {
                    out.println(1 + " " + 1);
                }
            }
        } else {
            int X = 10000000;
            for (int i = 0; i < m; i++) {
                out.println(i + " " + (i * i + X));
            }
            for (int i = 0; i < n - m; i++) {
                out.println(i + " " + (-i * i - X));
            }
        }
        out.close();
    }
}