Consider the following strange game. There is a \textbf{1}×\textbf{2n} board with cells numbered \textbf{1..2n} from left to right. Each of the first \textbf{n} cells is occupied by a token. All other cells are initially empty. Alice and Bob move one by one: each move consists in choosing a token such that the right neighboring cell is unoccupied and moving the token to this empty cell. The player who can't make a move loses the game. Having played thousands of games, Alice and Bob made a really unexpected conjecture: the result of the game depends only on \textbf{n}. But they are not sure about this. So they decided to check each possible sequence of moves for some \textbf{n}. Each play lasts for \textbf{1} minute. Your task is to calculate time it will take Alice and Bob to verify the conjecture. \InputFile One line containing an integer \textbf{1} ≤ \textbf{n} ≤ \textbf{30}. \OutputFile Write one integer --- time in minutes.