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 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:
a sonata is a piece of music for one instrument or one instrument with another instrument accompanying.

Ex Output:
sonata


Ex Input:
sonic firestorm is the second studio album by english power metal band dragonforce released through on may 11, 2004.

Ex Output:

sonic firestorm