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:
goldenrods are any of the about 150 species of weedy herbs that make up the genus solidago.

Ex Output:
goldenrod


Ex Input:
a marriage proposal is when one person in a relationship asks the other person to marry them.

Ex Output:
marriage proposal


Ex Input:
karur district is a district located very centrally along the kaveri and amaravathi rivers in the indian state of tamil nadu.

Ex Output:

karur district