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.

The single line contains two integers $ n $ and $ m $ ( $ 3

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.