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.

Input: Consider Input: Sentence1: Interestingly, a squid is also a mollusk. 
Sentence2: squids have a circulatory system with one or two hearts that pump blood.

Output: squid


Input: Consider Input: Sentence1: chemical splashing can cause harm to humans. 
Sentence2: chemical splashing can cause harm to animals.

Output: cause


Input: Consider Input: Sentence1: radioactive dating is used to determine the age of fossils. 
Sentence2: Fossil Petrified wood is the state fossil.


Output: fossils