Find the Unique Number

Your task is to implement a program that finds the unique number in an array in which every other number appears exactly twice. The idea is based on the property of the bitwise XOR operation, where a \oplus a = 0 and a \oplus 0 = a. Hence, if you XOR all the numbers together, the pairs cancel each other out and only the unique number remains.

More formally, given an array \(a\) of integers, there exists exactly one integer that occurs only once while every other element appears twice. Your program should read the array from standard input and output the unique element to standard output.

inputFormat

The input consists of a single line with space-separated integers representing the array. There is no separate number indicating the array size; all numbers on the line are part of the array.

outputFormat

Output a single integer which is the unique number that appears exactly once in the array.

4 3 2 4 1 3 2

1