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: cut : sword. wash : ?
Example Output: soap

Example Input: unlock : key. sweep : ?
Example Output: broom

Example Input: spread : knife. vacuum : ?
Example Output:
vacuum