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: Evaporation of sweat uses energy, and the energy comes from body heat. 
Sentence2: Evaporation of sweat uses energy, and the energy comes from exercise.

Output: Evaporation


Input: Consider Input: Sentence1: friction causes an object to lose energy. 
Sentence2: Friction occurs when surfaces rub together.

Output: friction


Input: Consider Input: Sentence1: Butter is a fat that is a solid at room temperature. 
Sentence2: Some fats are more likely to cause heart disease.


Output: fat