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: a battery converts chemical energy into electrical energy. 
Sentence2: Battery electricity comes conversion.

Output: battery


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: chemical weathering causes iron in rock to oxidize. 
Sentence2: chemical weathering causes redness of the rocks containing iron.


Output: causes