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: if soil is permeable then water easily flows through that soil. 
Sentence2: The increase in permeability is caused by the formation and expansion of ice in the soil.

Output: permeable


Input: Consider Input: Sentence1: camouflage is used for protection by prey against predators. 
Sentence2: blending is used for protection.

Output: protection


Input: Consider Input: Sentence1: absorbing sunlight causes objects to heat. 
Sentence2: Leaves absorb sunlight.


Output: absorbing