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A15968. Max to the Right of Min

编程题 普及/提高-

题目描述

You are given a permutation $p$ of length $n$ — an array, consisting of integers from $1$ to $n$ , all distinct.

Let $p_{l,r}$ denote a subarray — an array formed by writing down elements from index $l$ to index $r$ , inclusive.

Let $\mathit{maxpos}_{l,r}$ denote the index of the maximum element on $p_{l,r}$ . Similarly, let $\mathit{minpos}_{l,r}$ denote the index of the minimum element on it.

Calculate the number of subarrays $p_{l,r}$ such that $\mathit{maxpos}_{l,r} > \mathit{minpos}_{l,r}$ .

输入格式

The first line contains a single integer $n$ ( $1 \le n \le 10^6$ ) — the number of elements in the permutation.

The second line contains $n$ integers $p_1, p_2, \dots, p_n$ ( $1 \le p_i \le n$ ). All $p_i$ are distinct.

输出格式

Print a single integer — the number of subarrays $p_{l,r}$ such that $\mathit{maxpos}_{l,r} > \mathit{minpos}_{l,r}$ .

输入输出样例

输入 #1
3
1 2 3
输出 #1
3
输入 #2
6
5 3 6 1 4 2
输出 #2
4
输入 #3
10
5 1 6 2 8 3 4 10 9 7
输出 #3
38
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