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: Lancelet larvae are free-swimming. 
Sentence2: some larvae lack a hardened backbone.

Output: larvae


Input: Consider Input: Sentence1: Mitosis is cell division. 
Sentence2: Chromosomes are the form of the genetic material of a cell during mitosis.

Output: Mitosis


Input: Consider Input: Sentence1: Mutations may change the structure of a chromosome or just change a single nucleotide. 
Sentence2: DNA is made up of nucleotides.


Output: nucleotide