Lonely Number
By Gabriel Duarte, UNIFESO 
Brazil
By Gabriel Duarte, UNIFESO Brazil
You will be given an array of N numbers, where everyone will be in pairs. But one of those numbers ended up without peer, you can identify what is that number?
For example, A = {1, 1, 3, 3, 5, 5, 5}, the number stood alone was 5.
The input consists of several test cases. Each test case is composed of a line having an integer N (1 ≤ N < 10^5), followed by N number A (1 ≤ A ≤ 10^12).
For each test case print only the number that stood alone. It is guaranteed that only one number is alone
| Input Sample | Output Sample |
|
5 |
4 |