Prompt user to enter integer [on hold]

I have tried everything I can think of but nothing is working for this problem...

Prompt the user to enter an integer n. If n is odd, then compute the following jump-factorial: 1*3*5*7*…*n; if n is even, compute the following jump-factorial: 2*4*6*…*n; if n is negative or zero, the result is 0. Finally, output the result.