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: Centrioles come in pairs. 
Sentence2: Something that comes in pairs are organelles involved in cell division.

Output: come


Input: Consider Input: Sentence1: Bamboos are vigorous, rugged plants. 
Sentence2: Bamboo continue to grow throughout their lives.


Output: Bamboos