When traveling through Serbia and also Montenegro, you will notice use of two alphabets: Cyrillic and Latin. If you have to read names of the streets for instance, it might be useful to have both alphabets at hand.
Visit following link at Wikipedia for comparison between them: http://en.wikipedia.org/wiki/Serbian_language
For Macedonian (slightly different) version of the alphabet see: http://en.wikipedia.org/wiki/Macedonian_alphabet.