Tiling of the rectangle m×n dominoes is called stable, if there is no line intersecting the interior of the rectangle m×n and does not intersect the interior of any of dominoes.
For example, shown in the illustration of tiling (a) and (b) - solid, and tiling (c) and (d) - no.
And as there are solid rectangle tilings m×n?
The first line of two positive integers m and n (1 ≤ m ≤ 8; 1 ≤ n ≤ 16) — the width and height of the board.
Bring out one number - the number of solid tiles of the rectangle.
Clarification
We give all solid tiles in a rectangle of 5×6: