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: Babies that are very large or very small at birth are less likely to survive. 
Sentence2: Poor nutrition while in the womb is the major reason why babies are small at birth.

Output: birth


Input: Consider Input: Sentence1: Ice is frozen water. 
Sentence2: ice expands.

Output: Ice


Input: Consider Input: Sentence1: Basically, fiber is cellulose . 
Sentence2: Cells walls are fiber.


Output: fiber