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.

Input: Consider Input: spintronics is a kind of electronics that uses the tiny magnetic fields that come from electrons as well as their electric charge.

Output: spintronics

Input: Consider Input: platinum is a soft, heavy, white metal.

Output: platinum

Input: Consider Input: a tension headache is a common form of headache.
Output: tension headache