Pair Sum Possibility

You are given a list of integers and a target integer \( T \). Your task is to determine whether there exists a pair of distinct integers in the list whose sum equals \( T \). If such a pair exists, print POSSIBLE; otherwise, print IMPOSSIBLE.

Note: Two integers are considered distinct if they are at different positions in the list even if they have the same value.

Example:

• Input: 4 9 followed by 2 7 11 15
• Output: POSSIBLE

Use efficient methods as the input list can be large.

inputFormat

The first line of input contains two integers \( n \) and \( T \), where \( n \) denotes the number of elements in the list and \( T \) is the target sum.

The second line contains \( n \) space-separated integers.

outputFormat

Output a single line with the string POSSIBLE if there exists a pair of distinct integers such that their sum equals \( T \); otherwise, output IMPOSSIBLE.

4 9
2 7 11 15

POSSIBLE