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: Contact with infected blood, contaminated needles. 
Sentence2: scraping oneself on an infected needle may cause infection.

Ex Output:
infected


Ex Input:
Sentence1: Tree-ring dating the 1700 Cascadia earthquake. 
Sentence2: estimating the age of trees can be used in reviewing earthquake history.

Ex Output:
earthquake


Ex Input:
Sentence1: Reproduction is the process by which organisms give rise to offspring. 
Sentence2: Then, the lowest energy offspring are used as parents for the next generation.

Ex Output:

offspring