1.用戶登陸(三次機會重試)input
n = 1登錄
while n < 4循環
user = input(">>>")密碼
pwd = input(">>>")while
if user == "alex" and pwd == ("123")錯誤
print('歡迎登陸‘’)
break 終止全部循環
else
print(‘用戶密碼錯誤’)
n = n + 1