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: Combustion generates toxic fumes. 
Sentence2: High temperatures can cause toxic fumes.

Output: fumes


Input: Consider Input: Sentence1: Runoff water is wasted water. 
Sentence2: Streams may start with wasted water.

Output: wasted


Input: Consider Input: Sentence1: Mutations that lead to cancer usually occur in genes that control the cell cycle. 
Sentence2: a mutation in cells usually occur in genes that control the cell cycle.


Output: cell