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.

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

Ex Output:
feeders


Ex Input:
Sentence1: the Earth being tilted on its rotating axis causes seasons. 
Sentence2: the planet's orbit and tilt causes seasons.

Ex Output:
seasons


Ex Input:
Sentence1: a meter stick is used to measure distance. 
Sentence2: a meter stick is used to calculate distance.

Ex Output:

distance