Count Distinct Pairs

Given an integer array arr and an integer target, your task is to count the number of distinct pairs \( (i, j) \) (with \( i < j \)) such that \( arr[i] + arr[j] = target \). Note that a pair is defined by the indices and different occurrences of the same number are considered distinct if they occur at different positions.

For example, if arr = [1, 5, 7, -1, 5] and target = 6, the valid pairs are \( (0, 1) \), \( (0, 4) \), and \( (2, 3) \), yielding a total count of 3.

Please read the input from standard input and output the result to standard output.

inputFormat

The first line of input contains two integers n and target, where n is the number of elements in the array.

The second line contains n space-separated integers representing the array arr.

If n = 0, the second line will be empty.

outputFormat

Output a single integer, representing the number of distinct pairs \( (i, j) \) such that \( i < j \) and \( arr[i] + arr[j] = target \).

5 6
1 5 7 -1 5

3