Find the Unique Integer

You are given a list of integers in which every integer appears exactly twice except for one unique integer that appears only once. Your task is to find and print this unique integer.

You may recall that the bitwise XOR operator (\(\oplus\)) has many useful properties, one of which is that for any integer \(a\), \(a \oplus a = 0\) and \(0 \oplus a = a\). Using these properties, you can solve the problem in linear time with constant extra space.

inputFormat

The input is read from standard input (stdin) and consists of two lines. The first line contains a single integer \(n\) representing the number of elements in the list. The second line contains \(n\) space-separated integers which form the list.

outputFormat

Print the unique integer which appears exactly once in the list to standard output (stdout).

5
2 3 2 4 4

3