Two analogies that relate places/locations to the associated travel mode is given in the form "A : B. C : ?". "A : B" relates place A to travel mode B. Your task is to replace the question mark (?) with the appropriate travel mode for the given place C, following the "A : B" relation.

Ex Input:
museum : bus. downtown : ?

Ex Output:
subway


Ex Input:
office : car. island : ?

Ex Output:
boat


Ex Input:
airport : train. mainland : ?

Ex Output:

boat