1) it is ill-formed. Case matters here and condition should be encased in parentheses.
2) What is w and aWhere are they declared?
3) One string cannot be equal to two different strings, in the same way there are no numbers which equals 3 and 4 simultaneously.
It looks like you want the user to enter a string in the format of "a, b, c" where 'a' 'b' and 'c' are whichever letters they want to input. Simply checking if the string is equal to any individual letter won't work if they decide to input more than one. You can either 1. Restrict input to to one letter 2. Divide the input string into an array of char's based on the commas inputted 3. Use string::find to check if the input contains a character without having to parse the string yourself. The last option would probably be the easiest, but you'll need to change your "ww" option to something else, otherwise input.find("w") will return true for the inputs 'w' and "ww" without being able to differentiate them.
Quick example of how to use find:
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string input;
getline(cin,input);
if (input.find("w")!=string::npos)
{
//we have a 'w' input
}