Nike blazer sizes ... helpp?

iwant to order a pair of new nike blazers.. tht havent come out in stores... sooo when it asks for sizes it says 2c-10c.. wht does the little c mean ? cause im a 4.5 in the nike blazers itried on at kids footlocker.. but there are the same ones tht say 10.5c-1.5y.. idk wht the little c and y mean.. can someone tell me?