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:
stir : spoon. cut : ?

Ex Output:
scissors


Ex Input:
vacuum : vacuum. spread : ?

Ex Output:
knife


Ex Input:
iron : iron. crack : ?

Ex Output:

nutcracker