PAT basic1001-1005（Python版）

from sys import exit
x = int( raw_input() )
path = 0

while 1:
if x == 1:
break

if x % 2 == 0:
x /= 2
else:
x = ( 3 * x + 1 ) / 2

path += 1

if x == 1:
break

print path
exit(0)

from sys import exit
str = raw_input()
sum = 0

for i in str:
sum += int(i)

sumStr = '%d' % sum
str = ""
for i in range(len(sumStr)):
if i == len(sumStr)-1:
flag = ''
else:
flag = ' '

if sumStr[i] == '1':
str += 'yi' + flag
if sumStr[i] == '2':
str += 'er' + flag
if sumStr[i] == '3':
str += 'san' + flag
if sumStr[i] == '4':
str += 'si' + flag
if sumStr[i] == '5':
str += 'wu' + flag
if sumStr[i] == '6':
str += 'liu' + flag
if sumStr[i] == '7':
str += 'qi' + flag
if sumStr[i] == '8':
str += 'ba' + flag
if sumStr[i] == '9':
str += 'jiu' + flag
if sumStr[i] == '0':
str += 'ling' + flag

print str
exit(0)

from sys import exit

def isValid( strList ):
if strList.count('P') != 1 or strList.count('T') != 1:
return 1

pIndex = strList.index('P')
tIndex = strList.index('T')

if pIndex == 0 and tIndex == 1:
return 1

listLen = len(strList)
if (pIndex * (tIndex - pIndex-1) != listLen - 1 - tIndex):
return 1

keyNum = 0
for i in strList:
if i == 'A' or i == 'P' or i == 'T':
keyNum += 1

if len(strList) != keyNum:
return 1
else:
return 0

num = int(raw_input())
list = []

for i in range(num):
str = raw_input()
for j in str:
list.append(j)
if isValid(list) == 0:
print 'YES'
else:
print 'NO'
list = []

exit(0)

from sys import exit
num = input()
max = []
min = []

for i in range(num):
stud = raw_input().split()
if len(max) == 0 or int(stud[2]) > int(max[2]):
max = stud

if len(min) == 0 or int(stud[2]) < int(min[2]):
min = stud

print max[0], max[1]
print min[0], min[1]
exit(0)

from sys import exit

def addFact( factList, keyList, key ):
if key in factList or key in keyList:
return 1
keyList.append(key)
factList.append(key)

while True:
if key == 1:
if not key in factList:
factList.append(key)
break
if key % 2 == 0:
key /= 2
else:
key = ( 3 * key + 1 ) / 2

if (not key in keyList):
if (not key in factList):
factList.append(key)
else:
keyList.remove(key)

num  = input()
numList = raw_input().split()
numList = [int(numList[i]) for i in range(len(numList))]
factList = []
keyList = []

for i in numList:
addFact(factList, keyList, i)

keyList.sort()
keyList.reverse()

for i in range(len(keyList)):
if i != len(keyList)-1:
print keyList[i],
else:
print keyList[i]

exit(0)