#!/usr/bin/python

### a simple program for computing factorial with recursion
### and iteration.

import sys


def factorial (n):
    if n == 1:
        return 1
    else :  
        return n * factorial(n - 1)

def iterFactorial (n) :
    retval = 1
    for i in range (1,n+1) :
        retval = retval * i
    return retval



if __name__ == "__main__" :
    ### argv[0] is the program name, as in C
    ### arguments begin with argv[1]
    ### int() converts a string to an integer
    if len(sys.argv) < 2 :
        print "Usage: simple-factorial.py <number>"
    else :
        print "Recursive version:", factorial(int(sys.argv[1]))
        print "Iterative version: ", iterFactorial(int(sys.argv[1]))