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: Some viruses live in a dormant state inside the body. 
Sentence2: a virus can live in the brain.

Output: viruses


Input: Consider Input: Sentence1: the emission of sulfur dioxide causes acid rain. 
Sentence2: the emission of sulfur dioxide causes soil weathering.

Output: causes


Input: Consider Input: Sentence1: a flashlight converts chemical energy into light energy. 
Sentence2: Light is electromagnetic energy in the form of waves.


Output: energy