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: Rainy clouds cause rain, and excess water vapor from clouds is the basis of rainbows. 
Sentence2: Condensation can lead to rain.

Ex Output:
rain


Ex Input:
Sentence1: Mollusks live in most terrestrial, freshwater, and marine habitats. 
Sentence2: Clams live in freshwater habitats.

Ex Output:
freshwater


Ex Input:
Sentence1: After a seed is planted it is watered. 
Sentence2: seeds need water.

Ex Output:

seed