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.

Input: Consider Input: Sentence1: An organism can gain energy by assimilation or absorption of food. 
Sentence2: Organisms require food for growth.

Output: food


Input: Consider Input: Sentence1: if a neutral atom loses an electron then an atom with a negative charge will be formed. 
Sentence2: Ice crystals that are formed have a negative charge.

Output: charge


Input: Consider Input: Sentence1: We learned about desert plants and how they adapt themselves to the hot dry desert environment so they can survive. 
Sentence2: Desert plants conserve water to survive in the desert.


Output: desert