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: a dandelion is a flower.

Output: dandelion


Input: Consider Input: the palaeoptera is the group of primitive (basal) winged insects which do not fold the wings back over the abdomen, as neoptera do.

Output: palaeoptera


Input: Consider Input: a hapax legomenon is a word that is only occurs once in a corpus of text.


Output: hapax legomenon