Set of Points
Description
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.
The single line contains two integers n and m (3 ≤ m ≤ 100, m ≤ n ≤ 2m).
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.
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.
Samples
4 3
0 0
3 0
0 3
1 1
6 3
-1
6 6
10 0
-10 0
10 1
9 1
9 -1
0 -2
7 4
176166 6377
709276 539564
654734 174109
910147 434207
790497 366519
606663 21061
859328 886001