Problem:
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

3 6
7
5
7

Sample Output 1

5

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

0

Sample Input 3

7 26
10
20
30
40
30
20
10

Sample Output 3

13

Solution in Ruby (2.3.3) (judge verdict: Time Limit Exceeded)

BIT=[0]*200001
def add x,v;(BIT[x]+=v;x+=x&-x)while BIT[x];end
def sum x;s=0;(s+=BIT[x];x&=x-1)while x>0;s;end

n,k=gets.split.map &:to_i
ar=(1..n).map{gets.to_i}

list = ar.inject([0]){|s,r|s<<(s[-1]+r-k)}[1..-1]

rank = list.uniq.sort

ans = list.count{|i|i>=0}

list.each{|i|
  x=rank.index(i)+1
  ans += sum(x)
  add(x,1)
}
p ans