CF452F Permutation

You are given a permutation of numbers from $ 1 $ to $ n $ . Determine whether there's a pair of integers $ a,b $ $ (1

First line consists of a single integer $ n $ ( $ 1

Print "YES", if such a pair exists, "NO" otherwise (in both cases without quotes, the answer is case insensitive).

In the second example $ 2 $ is between $ 1 $ and $ 3 $ . Additionally $ 4 $ is between $ 3 $ and $ 5 $ .