Read a $2-$character string from input into variable userString. Declare a Boolean variable isValid and assign isValid with true if the following conditions are met:

userString does not contain two of the same character.

For alphabetic characters, userString does not contain two of the same letter $($regardless of case$).$

Otherwise, assign isValid with false.

Ex: If the input is d$.,$ then isValid is assigned with true, so the output is:

String accepted

Ex: If the input is Rr$,$ then isValid is assigned with false, so the output is:

String not accepted

Note: Use getline$($cin$,$ userString$)$ to read the entire line from input into userString.