Polygonal chain - 2#150

Polygonal chain - 2

1 second
128 megabytes
Hard
prb150

Find the number of different polygonal chains of minimal length that connect the origin to the point M(x, y), where each consecutive segment is perpendicular to the previous one and each segment has unit length.

Input

Two integers — the coordinates of point M(x, y), where -20 \le x, y \le 20.

Output

Print the number of possible polygonal chains of minimal length.

Examples

Example 1

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