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: a thermometer is used to measure temperature. 
Sentence2: a thermometer is used to measure heat.

Output: a


Input: Consider Input: Sentence1: a flashlight converts chemical energy into light energy. 
Sentence2: Only as long as there are batteries in the flashlight, the flashlight will function.

Output: flashlight


Input: Consider Input: Sentence1: Chloroplasts are organelles that are found in the cells of plants and algae. 
Sentence2: Chloroplasts are organelles that are found in the cells of mosses.


Output: Chloroplasts