Home

Contest: Task: Related: TaskB TaskD

Score : $600$ points

Problem Statement

You are given an integer sequence of length $N$, $a =$ {$a_1, a_2, …, a_N$}, and an integer $K$.

$a$ has $N(N+1)/2$ non-empty contiguous subsequences, {$a_l, a_{l+1}, …, a_r$} $(1 ≤ l ≤ r ≤ N)$. Among them, how many have an arithmetic mean that is greater than or equal to $K$?

Constraints

All input values are integers.
$1 ≤ N ≤ 2 \times 10^5$
$1 ≤ K ≤ 10^9$
$1 ≤ a_i ≤ 10^9$

Input

Input is given from Standard Input in the following format:

$N$ $K$
$a_1$
$a_2$
$:$
$a_N$

Output

Print the number of the non-empty contiguous subsequences with an arithmetic mean that is greater than or equal to $K$.

Sample Input 1

Sample Output 1

All the non-empty contiguous subsequences of $a$ are listed below:

{$a_1$} = {$7$}
{$a_1, a_2$} = {$7, 5$}
{$a_1, a_2, a_3$} = {$7, 5, 7$}
{$a_2$} = {$5$}
{$a_2, a_3$} = {$5, 7$}
{$a_3$} = {$7$}

Their means are $7$, $6$, $19/3$, $5$, $6$ and $7$, respectively, and five among them are $6$ or greater. Note that {$a_1$} and {$a_3$} are indistinguishable by the values of their elements, but we count them individually.

Sample Input 2

1 2
1

Sample Output 2

Sample Input 3