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: Most soil nutrients are cations. 
Sentence2: decomposition increases the amount of cations in the soil.

Ex Output:
cations


Ex Input:
Sentence1: evaporation can be used for separating a solute from a solvent in a solution. 
Sentence2: Evaporation can be used for segregation a solute from a solvent in a solution.

Ex Output:
a


Ex Input:
Sentence1: Animated maps show the birds flying along their actual migration paths. 
Sentence2: Earth's magnetic patterns are used so that birds can fly along their migration paths.

Ex Output:

along