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.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.StringTokenizer;


public class B277 {
    
    static StringTokenizer st;
    static BufferedReader in;
    static PrintWriter pw;
    
    public static void main(String[] args) throws IOException {
        in = new BufferedReader(new InputStreamReader(System.in));
        pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
        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 1");
            }
            if (n==4) {
                System.out.println("0 0");
                System.out.println("1 1");
                System.out.println("1 2");
                System.out.println("2 0");
            }
            if (n >= 5) {
                System.out.println(-1);
            }
            return;
        }
        int x = 0, y = 10000, delta = 1;
        for (int i = 1; i <= m; i++) {
            System.out.println(x+" "+y);
            y += delta;
            x++;
            delta++;
        }
        x = 0; y = -10000; delta = 1;
        for (int i = 1; i <= n-m; i++) {
            System.out.println(x+" "+y);
            y -= delta;
            x++;
            delta++;
        }
        pw.close();
    }
    private static int nextInt() throws IOException{
        return Integer.parseInt(next());
    }
    
    private static long nextLong() throws IOException{
        return Long.parseLong(next());
    }
    
    private static double nextDouble() throws IOException{
        return Double.parseDouble(next());
    }
    
    private static String next() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }
}