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.

Ex Input:
the flag of thailand has five stripes in the colours red, white, and blue.

Ex Output:
flag of thailand


Ex Input:
the diplura are a biological order.

Ex Output:
diplura


Ex Input:
blood on the dance floor: history in the mix is a remix album by michael jackson.

Ex Output:

blood on the dance floor: history in the mix