Given a category and a set of five words, find the word from the set that does not belong (i.e. is the least relevant) with the other words in the category. Words are separated by commas.

Category: military rank 
Words: general, fighter, normal, major, lieutenant
normal

Category: computers 
Words: ram, file, prepare, keys, format
prepare

Category: military rank 
Words: common, captain, sergeant, admiral, general

common