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: Streams may start with runoff or water seeping out of a spring. 
Sentence2: streams may start with runoff or h2o seeping out of a spring.

Output: Streams


Input: Consider Input: Sentence1: Ice is frozen water. 
Sentence2: ice expands.

Output: Ice


Input: Consider Input: Sentence1: If there is an increase in UV radiation, the risks go up for all types of skin cancer. 
Sentence2: ozone depletion increases the risk for all types of skin cancer.


Output: cancer