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: Viruses are parasites of cells. 
Sentence2: Populations of viruses do not grow through division because they are parasites.

Ex Output:
are


Ex Input:
Sentence1: boiling is when liquids are heated above their boiling point. 
Sentence2: If the pressure is reduced, the boiling point is lowered.

Ex Output:
boiling


Ex Input:
Sentence1: Vision is our ability to see. 
Sentence2: Vision is important to hunt prey.

Ex Output:

Vision