#!/usr/bin/python3
from sys import argv
from time import time

usage = f'usage: {argv[0]} <number>'

if len(argv) != 2:
    print(usage)
    quit(1)


def is_even(num):
    if str(num)[-1] in ['0', '2', '4', '6', '8']:
        return True
    else:
        return False


try:
    num = int(argv[1])
except ValueError:
    print(usage)
    quit(1)
else:
    count = 0
    t1 = time()
    while num != 1:
        if is_even(num):
            num = int(num / 2)
        elif not is_even(num):
            num = 3 * num + 1
        count += 1
    t2 = time()
    print(f'program took {t2-t1} seconds to run {count} iterations')