In this task, you will be given a sentence, and you need to identify the set of coreference words. Coreferences are generally a set of words in the text that refer to the same person or thing. Your output set of coreference words must be strictly present in the given input sentence. Do not use any outside knowledge to create the set of coreference words. If there is a 'the' article before the person or thing you should include 'the' as well. Please separate the coreference words by commas in the output.

Example Input: The mechanic gave the clerk a present because he won the lottery .
Example Output: The, mechanic, he

Example Input: The laborer handed the assistant a hammer because she need to beat in a nail .
Example Output: the, assistant, she

Example Input: The chief returned a book to the librarian but he had damaged the book .
Example Output:
The, chief, he