Factorial Challenge

Calculate the factorial of (n! = 1 \times 2 \times 3 \times \dots \times n).

Challenge: Implement the solution without using any looping constructs (for, while).

inputFormat

A single integer (n) (where (0 \le n \le 20)) is provided on one line.

outputFormat

Output the computed factorial, (n!), of the given integer.

sample

0

1