Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Input: Consider Input: Sentence1: Sponges are filter feeders. 
Sentence2: Hawksbills feed primarily on filter feeders.

Output: feeders


Input: Consider Input: Sentence1: Information on DNA is organized into genes. 
Sentence2: DNA codes for proteins.

Output: DNA


Input: Consider Input: Sentence1: Radioactive isotopes are commonly used for dating . 
Sentence2: isotopes are used to determine the age of fossils.


Output: isotopes