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: Most soil nutrients are cations. 
Sentence2: decomposition increases the amount of cations in the soil.

Output: cations


Input: Consider Input: Sentence1: Mollusks are invertebrates such as the common snail. 
Sentence2: Another common snail is the decollate snail.

Output: snail


Input: Consider Input: Sentence1: Chloroplasts contain the green pigment chlorophyll. 
Sentence2: Photosynthetic Pigments Photosynthetic Pigments Pigments are colorful compounds.


Output: pigment