Problem Statement:
the product of an integer and all the integers below it; e.g. factorial four ( 4! ) is equal to 1x2x3x4 = 24.


Input Format:
Given a number x between 1 and 52 inclusive


Output Format:
print the factorial of x


Sample Input:
13


Sample Output:
6227020800





Added by: gammal
Added at: 2015-06-14 14:00:00 UTC
Time Limit: 1 second
Partial score: No