#!/usr/bin/python
###                          Simple python examples
### python/examples/fact.py
###                          David MacKay and Sanjoy Mahajan
Usage = """
$ ./fact.py 10
3628800
"""
import sys

def fact(n):
    """
    Recursive function for computing factorial
    >>> fact(10)
    3628800
    """
    if n == 0:
        return 1
    else:
        return n * fact(n-1)

if (len(sys.argv)>1) :    
    print fact(int(sys.argv[1]))
else:
    print "Too few arguments!"
    print Usage