F. Permutationtime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou 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.InputFirst line consists of a single integer n (1 ≤ n ≤ 300000) — the size of permutation.Second line contains n integers — the permutation itself.OutputPrint "YES", if such a pair exists, "NO" otherwise (in both cases without quotes, the answer is case insensitive).ExamplesInput41 3 4 2OutputNOInput51 5 2 4 3OutputYESNoteIn the second example 2 is between 1 and 3. Additionally 4 is between 3 and 5.
Input41 3 4 2
OutputNO
['data structures', 'divide and conquer', 'hashing', '*2700']