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: Basically, heat is energy. 
Sentence2: Head hair is especially important in preventing energy loss from the body.

Ex Output:
energy


Ex Input:
Sentence1: Fully cooking oysters kills the bacteria. 
Sentence2: Fully cooking oysters can prevent illness.

Ex Output:
Fully


Ex Input:
Sentence1: planting trees has a positive impact on an ecosystem. 
Sentence2: planting trees has a positive impact on humans.

Ex Output:

planting