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: a wildfire changes an ecosystem drastically. 
Sentence2: Forest fires change an ecosystem drastically.

Ex Output:
changes


Ex Input:
Sentence1: Clouds are one form of condensation. 
Sentence2: Clouds are one form of changing from a gas into a liquid by reducing heat energy.

Ex Output:
Clouds


Ex Input:
Sentence1: electrocution causes harm to an organism. 
Sentence2: Hair dryers with shock protection are also available and can prevent electrocution.

Ex Output:

electrocution