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.

Ex Input:
bake : oven. unlock : ?

Ex Output:
key


Ex Input:
bake : oven. vacuum : ?

Ex Output:
vacuum


Ex Input:
sweep : broom. eat : ?

Ex Output:

fork