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: Lancelet larvae are free-swimming. 
Sentence2: some larvae lack a hardened backbone.

Ex Output:
larvae


Ex Input:
Sentence1: Bacteria and Viruses Bacteria and viruses can cause diseases. 
Sentence2: bacteria can have a negative impact on an organism.

Ex Output:
Bacteria


Ex Input:
Sentence1: Earth orbiting the Sun causes seasons to change. 
Sentence2: Earth orbiting the Sun causes weather changes.

Ex Output:

Earth