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: DNA is made up of nucleotides. 
Sentence2: Mutations can change the structure of DNA.

Output: DNA


Input: Consider Input: Sentence1: After about a week the larvae leave the nodules and continue to develop into adult worms. 
Sentence2: larvae leave the nodules and continue to transform until having reproductive organs.

Output: larvae


Input: Consider Input: Sentence1: Legionnaires' disease is a type of pneumonia. 
Sentence2: Legionnaires' disease may be caused by an infection or injury of the lungs.


Output: Legionnaires'