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: a flashlight converts chemical energy into light energy. 
Sentence2: PALight Flashlights are the ultimate personal LED flashlights.

Output: flashlight


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

Output: feeders


Input: Consider Input: Sentence1: absorbing sunlight causes objects to heat. 
Sentence2: Heat can destroy tissue.


Output: heat