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: Most bryophytes are small. 
Sentence2: Most in the same group as mosses are small.

Ex Output:
small


Ex Input:
Sentence1: Refrigerators are major users of electricity. 
Sentence2: Keeping food fresh for a long period of time requires a lot of electricity.

Ex Output:
electricity


Ex Input:
Sentence1: Drought causes famine, which contributes to decentralization and unrest. 
Sentence2: A decrease in precipitation can cause famine.

Ex Output:

causes