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.

Ex Input:
Sentence1: Flies are insects with two wings. 
Sentence2: Flies are arthropods with two wings.

Ex Output:
Flies


Ex Input:
Sentence1: harming an animal species causes that animal 's population to decrease. 
Sentence2: Oil spill sare harmful to animals and the enviroment.

Ex Output:
harming


Ex Input:
Sentence1: Petals attract pollinators to the flower. 
Sentence2: Petals are great for potpourri or for making rose petal jelly.

Ex Output:

Petals