题目描述
Alice has recently received an array $a_1, a_2, \dots, a_n$ for her birthday! She is very proud of her array, and when she showed her friend Bob the array, he was very happy with her present too!
However, soon Bob became curious, and as any sane friend would do, asked Alice to perform $q$ operations of two types on her array:
- $1$ $x$ $y$: update the element $a_x$ to $y$ (set $a_x = y$).
- $2$ $l$ $r$: calculate how many non-decreasing subarrays exist within the subarray $[a_l, a_{l+1}, \dots, a_r]$. More formally, count the number of pairs of integers $(p,q)$ such that $l \le p \le q \le r$ and $a_p \le a_{p+1} \le \dots \le a_{q-1} \le a_q$.
Help Alice answer Bob's queries!
Input
The first line contains two integers $n$ and $q$ ($1 \le n, q \le 2 \cdot 10^5$) — the size of the array, and the number of queries, respectively.
The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ($1 \le a_i \le 10^9$) — the elements of Alice's array.
The next $q$ lines consist of three integers each. The first integer of the $i$-th line is $t_i$, the operation being performed on the $i$-th step ($t_i = 1$ or $t_i = 2$).
If $t_i = 1$, the next two integers are $x_i$ and $y_i$ ($1 \le x_i \le n$; $1 \le y_i \le 10^9$), updating the element at position $x_i$ to $y_i$ (setting $a_{x_i} = y_i$).
If $t_i = 2$, the next two integers are $l_i$ and $r_i$ ($1 \le l_i \le r_i \le n$), the two indices Bob asks Alice about for the $i$-th query.
It's guaranteed that there is at least one operation of the second type.
Output
For each query of type $2$, print a single integer, the answer to the query.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
样例输出
提示
For the first query, $l = 2$ and $r = 5$, and the non-decreasing subarrays $[p,q]$ are $[2,2]$, $[3,3]$, $[4,4]$, $[5,5]$, $[2,3]$ and $[4,5]$.