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: Blood type is important for medical reasons. 
Sentence2: Type O is important for medical reasons.

Ex Output:
important


Ex Input:
Sentence1: Bryophytes occupy niches in moist habitats. 
Sentence2: Animals and plants that live in the same place and share resources form a community biome niche .

Ex Output:
niches


Ex Input:
Sentence1: If Arctic foxes are in too cool weather, they warm up by their thick fur. 
Sentence2: foxes warm up with fur.

Ex Output:

foxes