CF277B.Set of Points

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.

平面上一组点的凸性（convexity）是指能构成凸多边形的最大子集的大小。你的任务是构造一个包含 $ n $ 个点的点集，使其凸性恰好为 $ m $。该点集不得包含共线的三点。

The single line contains two integers n and m (3 ≤ m ≤ 100, m ≤ n ≤ 2_m_).

单行包含两个整数 $n$ 和 $m$（$3 \leq m \leq 100$，$m \leq n \leq 2m$）。

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.

如果无解，输出 -1。否则，输出 $n$ 对整数——即任意一个凸性为 $m$ 的点集的各点坐标。坐标的绝对值不得超过 $10^8$。