Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

Input: Consider Input: the boeing monomail was a monoplane instead of a biplane.

Output: boeing monomail


Input: Consider Input: the embassy of russia in copenhagen is the embassy of russia to denmark.

Output: embassy of russia in copenhagen


Input: Consider Input: a sphinx is a mythological figure, which looks like a lion with a human head.


Output: sphinx