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.

Example Input: airport : taxi. washington : ?
Example Output: train

Example Input: washington : train. mainland : ?
Example Output: boat

Example Input: canada : car. museum : ?
Example Output:
bus