Count Distinct Pairs with Given Sum

Given an integer array \(A\) and an integer target \(T\), count the number of distinct pairs \((i, j)\) such that \(i < j\) and \(A[i] + A[j] = T\).

Note: For any pair formed by two identical numbers \(x\) (i.e. when \(x = T-x\)), the number of pairs is given by the binomial coefficient \( \binom{n}{2} = \frac{n \times (n-1)}{2} \ \).

The input is given via standard input where the first line contains an integer \(n\) (the number of elements in the array), followed by a line with \(n\) integers (the array elements), and finally a line with the target value \(T\). The output is a single integer representing the count of distinct pairs.

Example:

Input:
5
1 5 7 -1 5
6
Output:
3

</p>

inputFormat

The input is read from standard input (stdin). The format is as follows:

• The first line contains an integer \(n\), the number of elements in the array.
• The second line contains \(n\) space-separated integers representing the array.
• The third line contains an integer \(T\), the target sum.

outputFormat

The output is printed to standard output (stdout) as a single integer denoting the count of distinct pairs \((i, j)\) such that \(i < j\) and \(A[i] + A[j] = T\).

## sample

5
1 5 7 -1 5
6

3