auto save

diy2.py

+i=3
+username = "python"
+userpassword = "123456"
+while True:
+    if i>0:
+        name = input("请输入用户名:")
+        if name!=username:
+            print("用户名错")
+            i=i-1
+            continue
+        password = input("请输入密码:")
+        if password!=userpassword:
+            print("密码错误")
+            i=-1
+            continue
+        if name == username and password == userpassword:
+            print("登录成功!")
+            break
+        else:
+            print("用户名密码错误重输")
+            i=i-1
+    print("限制")
+    exit()
+print("欢迎")
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