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: the emission of sulfur dioxide causes acid rain. 
Sentence2: the emission of sulfur dioxide causes soil weathering.

Ex Output:
causes


Ex Input:
Sentence1: high pressure systems cause clear weather. 
Sentence2: Weather Clear weather usually means good visibility.

Ex Output:
clear


Ex Input:
Sentence1: photosynthesis means producers convert from carbon dioxide, water, and solar energy into carbohydrates for themselves. 
Sentence2: photosynthesis means plants convert from carbon dioxide, water, and solar energy into carbohydrates.

Ex Output:

carbohydrates