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 Q]: the chinese postman problem is a mathematical problem of graph theory.
[EX A]: chinese postman problem

[EX Q]: michelbach-le-bas is a commune.
[EX A]: michelbach-le-bas

[EX Q]: the trypanosomatida are a group of unicellular kinetoplastids.
[EX A]:
trypanosomatida