Count Subarrays with Target Sum

Given an array of integers arr and an integer k, your task is to compute the total number of continuous subarrays whose sum equals k. A subarray is defined as a contiguous portion of the array.

You can use the following mathematical formulation: if we define the prefix sum as \(S(i) = \sum_{j=0}^{i} arr[j]\), then the sum of a subarray from index \(i\) to \(j\) is \(S(j) - S(i-1)\) (with \(S(-1)=0\)). The problem asks you to count the number of pairs \((i, j)\) such that \(S(j) - S(i-1) = k\).

inputFormat

The first line of input contains two integers n and k, where n is the number of elements in the array and k is the target sum. The second line contains n space-separated integers representing the array.

outputFormat

Output a single integer that represents the total number of continuous subarrays whose sum equals k.## sample

5 5
1 2 3 2 5

3