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: Plants use unsaturated fatty acids to store energy. 
Sentence2: Plants and fish contain fatty acids.

Output: Plants


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: Chloroplasts contain the green pigment chlorophyll. 
Sentence2: chlorophyll are photosynthetic.


Output: chlorophyll