following conditions are met:

inputString does not contain two of the same character.

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

Otherwise, assign isValid with false.

Ex: If the input is $v8,$ then isValid is assigned with true, so the output is:

String is valid

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

String is not valid

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