D. Xor Sum
time limit per test
1 second
memory limit per test
4 megabytes
input
standard input
output
standard output

You're given an array a with n elements.

Compute the xor sum of the elements that appear an odd number of times in the array a.

Input

The first line contains number n (1 ≤ n ≤ 3000000). The second line of the input contains n numbers, representing the array a. All elements of a are between 0 and 109

Output

The only line of the output contains the answer of the problem.

Examples
Input
5
4 4 3 3 4
Output
4