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: Most water comes from precipitation. 
Sentence2: aquatic animals require precipitation to survive.

Output: precipitation


Input: Consider Input: Sentence1: Plants that shed their leaves seasonally each year are called deciduous plants. 
Sentence2: vines shed their leaves seasonally each year.

Output: each


Input: Consider Input: Sentence1: Tooth decay is a destruction of the tooth enamel. 
Sentence2: Fluoride decreases the destruction of the enamel.


Output: a