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:
leni robredo (born april 23, 1965) is a filipina lawyer and politician.

Ex Output:
leni robredo


Ex Input:
teleportation is the supposed movement of matter from one point to another without travelling across the physical space between them.

Ex Output:
teleportation


Ex Input:
molar mass is the mass of a substance that has 6.022 × 10 atoms (avogadro's number).

Ex Output:

molar mass