Definition: You will be given a context and a verb separated with a newline character, and you have to answer if the given verb is a negation or not. A verb is a negation if it is not going to exist, not happen, or has no effect. The output should be "Yes" if the verb is a negation and "No" otherwise.

Positive Example 1 -
Input: Only the government of the United States can decide if it prefers this variant, continued the letter, which Castro read on a state television station broadcast. Gonzalez for months refused requests by Elian's Miami relatives to go to the United States to (claim) the boy.  
 Verb: claim
Output: Yes

Positive Example 2 -
Input: In Washington today, the Federal Aviation Administration (released) air traffic control tapes from the night the TWA Flight eight hundred went down.  
 Verb: released
Output: No

Negative Example 1 -
Input: WASHINGTON ( AP ) -- Preliminary DNA tests link a missing anti-abortion activist to a strand of hair found near where a sniper shot and killed a Buffalo, N.Y., doctor who (performed) abortions, a law enforcement official said Friday.  
 Verb: performed
Output: Yes

Negative Example 2 -
Input: He insisted that the NGO law " will not change our position at all ". " We won't (refuse) foreign donations, nor will we register as a 'foreign agent', " he said.  
 Verb: refuse
Output: No

Now complete the following example -
Input: Friday, an FBI official said authorities are pursuing more than 400 tips but have not pinned down Kopp's whereabouts.  In all candor, the FBI does not (know) where James Kopp is _ period,  said Paul Moskal, a spokesman for the bureau's Buffalo office.  
 Verb: know
Output: 


Answer: Yes