Read a $2-$character string from input into variable userString. Declare a Boolean variable noDuplicates and assign noDuplicates 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 noDuplicates with false.

Ex: If the input is f$.,$ then noDuplicates is assigned with true, so the output is:

String is valid

Ex: If the input is Nn$,$ then noDuplicates is assigned with false, so the output is:

String is not valid

Note: Use userString $=$ scnr$.$nextLine$()$ to read the entire line from input into userString.