Problems
Round table
Round table
In how many ways can we arrange $n$ different people around a round table? Two arrangements of people are considered identical if one arrangement can be obtained from the other by rotation.
\InputFile
One positive integer $n~(n \le 20)$.
\OutputFile
Print the number of ways to arrange $n$ different people around a round table.
Input example #1
4
Output example #1
6