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.

Ex Input:
Sentence1: If there is enough moisture in the clouds, rain is produced. 
Sentence2: Clouds lacking water reduces rainfall.

Ex Output:
clouds


Ex Input:
Sentence1: friction is used for stopping a vehicle by brakes. 
Sentence2: friction is used for stopping a car by brakes.

Ex Output:
brakes


Ex Input:
Sentence1: Running water is better able to dissolve oxygen and nutrients than standing water. 
Sentence2: Oxygen and nutrients dissolve easily in rivers.

Ex Output:

dissolve