A9471. Permutation

You are given a permutation of numbers from $1$ to $n$ . Determine whether there's a pair of integers $a,b$ $(1<=a,b<=n; a≠b)$ such that the element  (note, that it is usual division, not integer one) is between $a$ and $b$ in this permutation.

First line consists of a single integer $n$ ( $1<=n<=300000$ ) — the size of permutation.

Second line contains $n$ integers — the permutation itself.

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 $5$ .