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 chief gave the housekeeper a tip because he was satisfied .
Example Output: The, chief, he

Example Input: The developer built a website for the tailor because he is an expert in building websites .
Example Output: The, developer, he

Example Input: The physician told the nurse that he had been busy .
Example Output:
The, physician, he