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: Roundworms make up the phylum Nematoda. 
Sentence2: Also, nematoda and rotifera are important groups contributing to soils.

Output: Nematoda


Input: Consider Input: Sentence1: Caverns Secrets are hidden in caves. 
Sentence2: hidden caves are formed by carbonic acid in groundwater seeping through rock and dissolving limestone.

Output: are


Input: Consider Input: Sentence1: Weather refers to the conditions of the atmosphere from day to day. 
Sentence2: Weather refers to the conditions such as rain from day to day.


Output: Weather