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.

Example Input: wash : detergent. dry : ?
Example Output: cloth

Example Input: spread : knife. scrub : ?
Example Output: brush

Example Input: spread : knife. unlock : ?
Example Output:
key