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 british rail class 931 was reserved for former southern region electrical multiple units converted for departmental use.

Ex Output:
british rail class 931

Ex Input:
guido altarelli (july 12, 1941 - september 30, 2015) was an italian theoretical physicist.

Ex Output:
guido altarelli

Ex Input:
otto adolf eichmann (19 march 1906 in solingen - 31 may 1962 in ramla) was a german ss officer (he had the rank of ss-obersturmbannfuhrer, comparable with lieutenant colonel).

Ex Output:
adolf eichmann