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: 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: a stopwatch is used to measure time. 
Sentence2: Time can be measured with a clock or watch.

Ex Output:
measure


Ex Input:
Sentence1: Tobacco companies make cigarettes. 
Sentence2: smoking cigarettes decreases stamina.

Ex Output:

cigarettes