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: Antibiotics and vaccines are being stockpiled as Britain gears up to meet the bioterrorism threat. 
Sentence2: Antibiotics and vaccines are being stockpiled against another potential threat in the environment.

Output: Antibiotics


Input: Consider Input: Sentence1: a flower 's purpose is to produce seeds. 
Sentence2: Every job has meaning and purpose.

Output: purpose


Input: Consider Input: Sentence1: Any surface that has not been sterilized is likely to be covered with bacteria. 
Sentence2: Bacteria are the smallest of microscopic organisms.


Output: bacteria