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 static java.lang.System.in;
import static java.lang.System.out;

import java.io.*;
import java.util.*;

public class B277 {
	static final double EPS = 1e-10;
	static final int INF = 1 << 20;
	static final double PI = Math.PI;

	public static Scanner sc = new Scanner(in);
	StringBuilder sb = new StringBuilder();
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	public void run() throws IOException {
		String input;
		String[] inputArray;
		input = br.readLine();
		inputArray = input.split(" ");
		int n = Integer.valueOf(inputArray[0]);
		int m = Integer.valueOf(inputArray[1]);

		if (m==3 && n>=5) {
			ln("-1");
			return;
		}
		for (int x=0; x<m/2; x++)
			ln(-x + " " + (x*x+INF));
		for (int x=1; x<m-m/2+1; x++)
			ln(x + " " + (x*x+INF));
		for (int x=0; x<(n-m)/2; x++)
			ln(-x + " " + (-x*x-INF));
		for (int x=1; x<(n-m)-(n-m)/2+1; x++)
			ln(x + " " + (-x*x-INF));
	}

	public static void main(String[] args) throws IOException {
		new B277().run();
	}
	public static void ln(Object obj) {
		out.println(obj);
	}
}