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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
class MyClass
{
    public int comb(int _a, int _b, int[] date)
    {
        int a = _a, b = _b;
        double sum, count;
        int rc=0,flag=0;
        for (int i = 0; i < (1 << a); i++)
        {
            sum = 0;
            count = 0;
            flag = 0;
            for (int j = 0; j < a; j++)
            {
                if ((i & (1 << j)) > 0)
                {
                    if (flag == 2) { count = 0; break; }
                    flag = 1;
                    count++;
                    sum += date[j];
                }
                else if(flag == 1)
                {
                    flag=2;
                }
            }
            if(count > 0)
            {
                sum = sum / count;
                if (sum >= b) rc++;
            }
        }
        return rc;
    }
    static void Main()
    {
        String[] line = System.Console.ReadLine().Trim().Split(' ');
        int n = int.Parse(line[0]), m = int.Parse(line[1]);
        int[] d = new int[n];
        for (int i = 0; i < n; i++)
        {
            d[i] = int.Parse(System.Console.ReadLine().Trim());
        }

        int res = new MyClass().comb(n, m, d);
        System.Console.WriteLine(res);
    }
}