Consider an infinite checkered board. We call a \textit{path} from one cell to another sequence of cells, in which every two consecutive cells are adjacent to the side. Path length - the number of cells in it, not counting the initial value. We call the path \textit{simple} if it does not meet two identical cells. Fix the cells on the board. As there are simple ways of a given length, starting in the cage? \InputFile The first line of the input file is given an integer \textbf{n} (\textbf{0} ≤ \textbf{n} ≤ \textbf{22}). \OutputFile The first line of the output file output a single number - the number of paths of length \textbf{n} from this cell.