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: June Summer Triangle Three bright stars light up the summer sky. 
Sentence2: Nuclear reactions in stars cause them to brighten up the summer sky.

Output: bright


Input: Consider Input: Sentence1: friction causes the temperature of an object to increase. 
Sentence2: internal combustion engines get hot.

Output: temperature


Input: Consider Input: Sentence1: Sperm are deposited in the vagina during sexual intercourse. 
Sentence2: During sex, sperm is deposited into the woman's reproductive organ.


Output: Sperm