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.*;
import java.io.*;

public class solve {
	Scanner in;
	PrintWriter out;
	int[] k;
	int n, m;
	int[][] a;
	ArrayList<Integer>[] g;
	boolean f[][];
	boolean[] was;

	public void solve() throws IOException {
		n = in.nextInt();
		m = in.nextInt();
		if (m == 3) {
			if (n > 4) {
				System.out.println(-1);
			} else {
				if (n == 3) {
					System.out.println(0 + " " + 0);
					System.out.println(0 + " " + 1);
					System.out.println(1 + " " + 0);
				} else {
					System.out.println(0 + " " + 0);
					System.out.println(3 + " " + 0);
					System.out.println(0 + " " + 3);
					System.out.println(1 + " " + 1);
				}
			}
			return;
		}
		int x = - 100000000;
		int y;
		for (y = 0; y < m; y++) {
			System.out.println(x + " " + (y - 100000000));
			x += y + 1 + 100;
		}
		x = 100000000 - 3000000;
		y = 100000000 - 2999995;
		
		for (int i = 0; i < n - m; i++) {
			System.out.println((x + " " + (y + i)));
			x += n - m - i + 100;
		}
	}

	public void run() {
		try {
			in = new Scanner(System.in);
			out = new PrintWriter(System.out);

			solve();

			out.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		FastScanner(File f) {
			try {
				br = new BufferedReader(new FileReader(f));
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			}
		}

		String next() {
			while (st == null || !st.hasMoreTokens()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

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

	public static void main(String[] arg) {
		new solve().run();
	}
}