here's the needed output. btw there must be first a Password.txt and Username.txt

Default username must be : 123 default password : 123

Here's where the program starts

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LOG-IN

Username: "Input" Password: "Input"

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After logging and the password or username is wrong print "Username or password Error" Or if it was correct proceed to next step

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Menu

1 - Change Username

2 - Change Password

3 - View Username

4 - View Password

Choice : "Input"

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If he picked choice 1 or 2

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Change Username/Password

Old Username/password: New Username/password:

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If he picked choice 3 or 4

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View Username/Password

" " (new or default username or password must be shown here)