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: a solution is formed by one substance being dissolved in another substance. 
Sentence2: A solution is formed when limestone is dissolved in ocean water.

Output: formed


Input: Consider Input: Sentence1: Mad Cow disease is a concern. 
Sentence2: pathogens can cause Mad Cow.

Output: Cow


Input: Consider Input: Sentence1: moss causes chemical weathering. 
Sentence2: Bryophytes include the mosses and liverworts.


Output: moss