passwdList = ("nihao", "nihao1", "nihao2")
valid = False
count = 3
while count > 0:
input = raw_input("enter password: ")
# check for valid passwd
for eachPasswd in passwdList:
if input == eachPasswd:
valid = True
break
if not valid:
print "invalid input"
count -= 1
continue
else:
print 'Password check pass!'
break
if not valid:
print 'Password check Fail!'