# Round table

Execution time limit is 1 second

Runtime memory usage limit is 128 megabytes

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.

## Input

One positive integer $n(n≤20)$.

## Output

Print the number of ways to arrange $n$ different people around a round table.

## Examples

Input #1

Answer #1

Submissions 39

Acceptance rate 56%