Definition: In this task, you are given a context tweet, a question and corresponding answer of given question. Your task is to classify given passage into two categories: (1) "yes" if the given context is useful in answering the question, and (2) "no" if the given context is not useful.
Input: Context: David @Letterman announced he's retiring in 2015. It's been 31 incredible years. Television won't be the same without you, Dave.— Ellen DeGeneres (@TheEllenShow) April 3, 2014 Question: what country was the river distaster? Answer: china

no