On his quest to solve Terminus Est, Max finds an ancient scroll that claims to be the key to solving the problem.
The scroll proclaims:
The one to solve Terminus Est shall be able to recognize patterns.
Max interprets this as the ability to recognize arithmetic patterns.
Max defines an arithmetic pattern as a list () of integers where the difference between any adjacent pair is the same.
The difference of an adjacent pair of integers is defined as for all , .
Can you determine if a list of numbers is an arithmetic pattern?
The first line contains a single integer, . .
The next line describes the list of numbers by providing space separated integers where the th integer describes .
YES if the input list is an arithmetic pattern.
NO if the input list is not an arithmetic pattern.
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