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: hiding can be used for avoiding predators. 
Sentence2: Camouflage is used for avoiding predators.

Ex Output:
avoiding


Ex Input:
Sentence1: Specialization decreases mortality 12,13 and increases survival. 
Sentence2: evolving different adaptations increases survival.

Ex Output:
increases


Ex Input:
Sentence1: Blood pH may become unbalanced if the rate of breathing is too fast or too slow. 
Sentence2: Blood pH may become unstable if the rate of breathing is too fast or too slow.

Ex Output:

Blood