save project

a.py

 n = "python"
 n = "python"
 m = "123456"
 m = "123456"
-tn = input("账号：")
-tm = input("密码：")
-if tn==n and tm==m:
-    print("登录成功")
+while True:
+    tn = input("账号：")
+    tm = input("密码：")
+    if tn==n and tm==m:
+        print("登录成功")
+        break
+    else:
+        print("账号密码错误，请重新登录")
+print("欢迎来到贝尔编程")
+