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: If there is an increase in UV radiation, the risks go up for all types of skin cancer. 
Sentence2: Ozone depletion increases the risks for all types of skin cancer.

Ex Output:
all


Ex Input:
Sentence1: For example, insulin is a protein hormone. 
Sentence2: Insulin is produced in a part of the cell called the ribosome.

Ex Output:
insulin


Ex Input:
Sentence1: a mold spore has a negative impact on the respiratory system. 
Sentence2: A mold spore has a negative impact on the lungs.

Ex Output:

impact