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: Spikes are forceful the tidal waves of electric current. 
Sentence2: spikes come from tidal energy.

Ex Output:
Spikes


Ex Input:
Sentence1: If there is sun, there is sunlight, there is day. 
Sentence2: Energy enters ecosystems from the sun.

Ex Output:
sun


Ex Input:
Sentence1: Fungi are the only organisms that can decompose wood. 
Sentence2: Fungi are the only organisms that can decompose biodegradable products.

Ex Output:

Fungi