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: Algae have varied life cycles. 
Sentence2: And fish eat algae.

Output: Algae


Input: Consider Input: Sentence1: Examples of gametes are ova and spermatozoa. 
Sentence2: fertilization of ova and spermatozoa produces a diploid zygote.

Output: ova


Input: Consider Input: Sentence1: P16 is a regulator of the cell division cycle. 
Sentence2: Cancer is a disease that occurs when genes like P16 stop functioning properly.


Output: P16