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: when a river floods , that river deposits soil in flood plains. 
Sentence2: when a river floods, it deposits soil in generally marshy areas.

Ex Output:
deposits


Ex Input:
Sentence1: Cultivation is easier if soil is loose. 
Sentence2: soil with more oxygen is easier to cultivate.

Ex Output:
Cultivation


Ex Input:
Sentence1: Mutations are sources of variations in offspring. 
Sentence2: Mutations can occur during the reproduction process.

Ex Output:

Mutations