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: the mass of an object causes the gravitational force exerted by that object. 
Sentence2: gravitational force accelerates objects.

Output: force


Input: Consider Input: Sentence1: DNA is the stuff of life. 
Sentence2: chromosomes are the stuff of life.


Output: life