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 sifter is used for separating mixtures. 
Sentence2: a sifter is used for some recipes.

Output: sifter


Input: Consider Input: Sentence1: Dromaeosaurs are part of the theropod group of dinosaurs. 
Sentence2: Birds evolved from a group of bipedal dinosaurs that included Dromaeosaurs.

Output: Dromaeosaurs


Input: Consider Input: Sentence1: Ferns have no flowers, fruits or seeds. 
Sentence2: some plants have no flowers.


Output: flowers