MathLoops
Compute n! (n factorial), the product of all integers from 1 to n. By definition 0! = 1.
Input
A single integer n.
Output
Print n!.
Constraints
0 <= n <= 20
Example 1
Input
5
Output
120
5 * 4 * 3 * 2 * 1 = 120
Example 2
Input
0
Output
1
By definition 0! = 1.