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: Flowers produce seeds for reproduction. 
Sentence2: flowers require dispersal for reproduction.

Ex Output:
Flowers


Ex Input:
Sentence1: Specialization occurs when competing species evolve different adaptations. 
Sentence2: evolving different adaptations increases survival.

Ex Output:
adaptations


Ex Input:
Sentence1: Bladder infections can be treated with antibiotics prescribed by a doctor. 
Sentence2: Penicillin and tetracycline are potent antibiotics.

Ex Output:

antibiotics