The number N factorial, denoted by N!, is defined to be the product of the first N positive integers:

N! = 1 × 2 × . . . × N

For example:

5! = 1 × 2 × 3 × 4 × 5 = 120

7! = 1 × 2 × 3 × 4 × 5 × 6 × 7 = 5,040

Find N!, where N is a positive integer input by the user.