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.

Example Input: jan mlby is a former football player.
Example Output: jan mlby

Example Input: giorgio chiellini (born 14 august 1984) is an italian football player.
Example Output: giorgio chiellini

Example Input: watercress, "nasturtium officinale", is a plant which grows in water.
Example Output:
watercress