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: when a gas in an open container evaporates , that gas spreads out into the air. 
Sentence2: If you place gas in an open box it will evaporate and spread out into the air.

Output: gas


Input: Consider Input: Sentence1: An astronaut is a scientist who is a space explorer. 
Sentence2: Space explorers require preserved food for long flights.

Output: explorer


Input: Consider Input: Sentence1: if soil is permeable then water easily flows through that soil. 
Sentence2: water easily flows through the soil of hawaiian lavas.


Output: easily