Set of Points

题意翻译

- 你需要给出二维平面上的 $n$ 个坐标为整数的点，使得在这 $n$ 个点中： - 点数最多的凸包恰有 $m$ 个点。 - 没有三个点共线。 - 若无解，输出 ``-1``。 - $3 \leq m \leq 100, m \leq n \leq 2m$

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.

输入输出格式

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

输入样例 #1

4 3

输出样例 #1

0 0
3 0
0 3
1 1

输入样例 #2

6 3

输出样例 #2

-1

输入样例 #3

6 6

输出样例 #3

10 0
-10 0
10 1
9 1
9 -1
0 -2

输入样例 #4

7 4

输出样例 #4

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