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.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.HashSet;
import java.util.StringTokenizer;

public class D {
	BufferedReader in;
	StringTokenizer st;
	PrintWriter out;

	public void Solution() throws IOException {
		int n = nextInt();
		int m = nextInt();
		if (m == 3) {
			if (n == 3) {
				System.out.println(0 + " " + 0);
				System.out.println(0 + " " + 1);
				System.out.println(1 + " " + 0);
			}
			if (n == 4) {
				System.out.println(0 + " " + 0);
				System.out.println(3 + " " + 0);
				System.out.println(0 + " " + 3);
				System.out.println(1 + " " + 1);
			}

			if (n >= 5) {
				System.out.println(-1);
			}
		} else {
			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))) * -1);
			}
		}
	}

	public void run() throws IOException {
		try {
			// in = new BufferedReader(new FileReader(new File("input.txt")));
			// out = new PrintWriter(new File("output.txt"));
			in = new BufferedReader(new InputStreamReader(System.in));
			out = new PrintWriter(System.out);
			Solution();
			out.close();

		} catch (Exception e) {
			e.printStackTrace();
			System.exit(261);
		}
	}

	public String nextToken() throws IOException {
		if (st == null || !st.hasMoreTokens()) {
			st = new StringTokenizer(in.readLine());
		}
		return st.nextToken();
	}

	public long nextlong() throws IOException {
		return Long.parseLong(nextToken());
	}

	public int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

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