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A8939 | $Set of Points$

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内存限制256MB

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题目描述

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.

输入格式

The single line contains two integers $n$ and $m$ ( $3<=m<=100,m<=n<=2m$ ).

输出格式

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 $10^{8}$ in their absolute value.

输入输出样例

输入 #1

4 3

输出 #1

输入 #2

6 3

输出 #2

-1

输入 #3

6 6

输出 #3

输入 #4

7 4

输出 #4

176166 6377
709276 539564
654734 174109
910147 434207
790497 366519
606663 21061
859328 886001

C++ 编辑器

输入

输出