Two analogies that relate actions to the tools used to perform the action is given in the form "A : B. C : ?". "A : B" relates action A to tool B. Your task is to replace the question mark (?) with the appropriate tool for the given action C, following the "A : B" relation.

Input: Consider Input: spread : knife. unlock : ?

Output: key


Input: Consider Input: iron : iron. scrub : ?

Output: brush


Input: Consider Input: cook : stove. spread : ?


Output: knife