Pair Sum Problem

You are given a list of integers and a target sum T. Your task is to determine whether there exist two distinct elements in the list whose sum is equal to T. Formally, given a list of integers \(a_1, a_2, \ldots, a_n\) and an integer target \(T\), check if there exist two indices \(i\) and \(j\) (with \(i \neq j\)) such that:

\(a_i + a_j = T\)

If such a pair exists, output True; otherwise, output False.

inputFormat

The input is read from standard input and has the following format:

1. An integer \(n\) representing the number of elements in the list.
2. A line containing \(n\) space-separated integers representing the elements of the list. If \(n = 0\), this line will be empty.
3. An integer \(T\) which is the target sum.

outputFormat

Output a single line to standard output, which is either True or False, indicating whether there exists a pair of distinct numbers in the list that sum up to \(T\).

4
2 7 11 15
9

True