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: Enveloped viruses make their own membranes. 
Sentence2: Some viruses make their own membranes.

Ex Output:
make


Ex Input:
Sentence1: Soil Erosion Soil erosion is a natural process. 
Sentence2: wind and rain is a natural process.

Ex Output:
natural


Ex Input:
Sentence1: an earthquake causes the ground to shake. 
Sentence2: An earthquake is the shaking of the crust.

Ex Output:

shake