#! /usr/bin/env python3

import sys
import collatz

usage='usage: collatzSequence [number] prints the collatz sequence for the given number'

if len(sys.argv)<2:
    Print(usage)
    sys.exit()
number = sys.argv[1]

try:
    number = int(number)
except:
    print(usage)
    sys.exit()
seqLength = 0
while number != 1:
    number = collatz.nextInSequence(number)
    seqLength += 1
    print(number)
print('length of '+str(seqLength))