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: moss causes chemical weathering. 
Sentence2: If the moss was completely dried then it is dead.

Output: moss


Input: Consider Input: Sentence1: Among families with children the average number of offspring is 1.8. 
Sentence2: information in an organism's chromosomes cause genetic traits to be passed down to that organism's children.

Output: children


Input: Consider Input: Sentence1: detailed observation of celestial objects requires a telescope. 
Sentence2: Detailed observation of stars requires a telescope.


Output: a