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: Chordates have a complete digestive system and a closed circulatory system. 
Sentence2: All chordates are vertebrates.

Output: Chordates


Input: Consider Input: Sentence1: With a spatula, fold in flour mixture. 
Sentence2: a sifter is used for separating flour.

Output: flour


Input: Consider Input: Sentence1: Antigens are molecules that the immune system recognizes as foreign to the body. 
Sentence2: A molecule of carbohydrate or protein molecule the immune system recognizes as foreign to the body.


Output: body