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: hunting requires seeing prey. 
Sentence2: hunting requires seeing an animal.

Output: hunting


Input: Consider Input: Sentence1: Clouds are one form of condensation. 
Sentence2: Clouds are one form of changing from a gas into a liquid by reducing heat energy.

Output: Clouds


Input: Consider Input: Sentence1: dew is formed when water vapor condenses over night. 
Sentence2: Dew is formed when vapor changes to liquid.


Output: dew