Given boxes of dimensions 1 x n, 2 x n, 3 x n ........... k x n and a special box of height "h" and width "n".
In how many ways you can fill this special box using given boxes(you can use same box multiple times), provided you can place given boxes either horizontally or vertically i.e. box of dimension "1 x n" can be placed inside the special box, either 1xn or nx1 way.