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: friction causes the temperature of an object to increase. 
Sentence2: When we increase the temperature of objects, they always expand.

Output: increase


Input: Consider Input: Sentence1: Precipitation falls on the windward side of the mountain range. 
Sentence2: Mountains have higher precipitation than adjacent lowlands.

Output: Precipitation


Input: Consider Input: Sentence1: thirst is used to make an animal realize that it needs to replenish its bodily water by the body. 
Sentence2: dehydration is when an animal needs to replenish bodily water.


Output: animal