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

Output: ova


Input: Consider Input: Sentence1: Angiosperm sporophyte is dominant. 
Sentence2: Flowers form on angiosperms.

Output: Angiosperm


Input: Consider Input: Sentence1: Fertilization occurs when a sperm and an egg fuse to form a diploid zygote. 
Sentence2: a zygote is formed by an ovum.


Output: zygote