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:

// @author Sanzhar
import java.io.*;
import java.util.*;
import java.awt.Point;

public class Template {

    BufferedReader in;
    PrintWriter out;
    StringTokenizer st;

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

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

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

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

    public void run() throws Exception {
        //in = new BufferedReader(new FileReader("input.txt"));
        //out = new PrintWriter(new FileWriter("output.txt"));
        in = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
        solve();
        out.flush();
        out.close();
        in.close();
    }

    public void solve() throws Exception {
        int n = nextInt();
        int m = nextInt();
        if (m == 3) {
            if (n == 3) {
                out.println(0 + " " + 0);
                out.println(0 + " " + 1);
                out.println(1 + " " + 0);
                return;
            }
            if (n == 4) {
                out.println(0 + " " + 0);
                out.println(0 + " " + 10);
                out.println(10 + " " + 0);
                out.println(1 + " " + 1);
                return;
            }
            if (n >= 5) {
                out.println(-1);
                return;
            }
        }
        int x = 10000000;
        for (int i = 1; i <= m; i++) {
            out.println(i + " " + (x + i * i));
        }
        for (int i = 1; i <= n - m; i++) {
            out.println(i + " " + (-x - i * i));
        }
    }

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