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: bake : oven. unlock : ?
Example Output: key

Example Input: cook : pan. iron : ?
Example Output: iron

Example Input: cook : stove. sweep : ?
Example Output:
broom