input_count = input('自然数')
i = int(input_count)
while i!=1:
if i%2==1:
i = 3*i-1
else:
i = i//2
print(i)
aW5wdXRfY291bnQgPSBpbnB1dCgn6Ieq54S25pWwJykKIAppID0gaW50KGlucHV0X2NvdW50KQp3aGlsZSBpIT0xOgogICAgaWYgaSUyPT0xOgogICAgICAgIGkgPSAzKmktMQogICAgZWxzZToKICAgICAgICBpID0gaS8vMgogICAgcHJpbnQoaSk=