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<=≤<=*m*<=≤<=100,<=*m*<=≤<=*n*<=≤<=2*m*).
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.
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