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 vickers machine gun (also known as the vickers gun) was a machine gun that was used by the british army from 1912 to 1968.

Ex Output:
vickers machine gun


Ex Input:
the social democratic party of germany (german sozialdemokratische partei deutschlands or spd) is the oldest political party in germany that still exists, having been formed on 23 may 1863.

Ex Output:
social democratic party of germany


Ex Input:
oghi is a town in mansehra district, of khyber pakhtunkhwa province of pakistan.

Ex Output:

oghi