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.*;
import java.util.*;

public class Codeforces {
	FastScanner in;
	PrintWriter out;

	class Point {
		int x, y;

		public Point(int x, int y) {
			super();
			this.x = x;
			this.y = y;
		}
	}
	
	final int maxH = 300, maxW = 300000;
	final int maxCoord = (int) 1e8;
	ArrayList<Point> ans = new ArrayList<Codeforces.Point>();
	
	void draw1(int count, int x, int y) {
		int len = 100;
		for (int i = 0; i < count; i++) {
			ans.add(new Point(x, y));
			x += len;
			len++;
			y++;
		}
	}
	
	void draw2(int count, int x, int y) {
		int len = 200;
		for (int i = 0; i < count; i++) {
			ans.add(new Point(x, y));
			x += len;
			len--;
			y++;
		}
	}
	
	void solve() {
		int n = in.nextInt(), m = in.nextInt();
		draw1(m, -maxCoord + 10, -maxCoord + 10);
		draw2(n - m, maxCoord - 10 - maxW, maxCoord - 10 - maxH);
		
		if (m == 3 && n >= 5) {
			out.println(-1);
			return;
		}
		
		for (Point p : ans) {
			out.println(p.x + " " + p.y);
		}
	}

	void run() {
		in = new FastScanner();
		out = new PrintWriter(System.out);
		solve();
		out.close();
	}

	class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		FastScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));

		}

		String next() {
			while (st == null || !st.hasMoreTokens()) {

				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}
	}

	public static void main(String[] args) {
		new Codeforces().run();
	}
}