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 pH may become unbalanced if the rate of breathing is too fast or too slow. 
Sentence2: If Someone Is Hyperventilating Hyperventilation is caused by breathing too deeply, too fast.

Ex Output:
breathing


Ex Input:
Sentence1: Telephone Telephone calls are expensive. 
Sentence2: Communicating by transmitting sound is expensive.

Ex Output:
expensive


Ex Input:
Sentence1: Blood type is important for medical reasons. 
Sentence2: Type O is important for medical reasons.

Ex Output:

important