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.