You are given an array ~A~ of size ~N~ of numbers in which every number appears an even number of times except for one. Find that number.

Input Specifications

The first line of input will contain ~N~ ~(1 \le N \le 10^6)~, the size of the array, followed by array ~A~, where ~A_i~ ~(0 \le A_i \le 10^9)~.

Output Specifications

Output one integer, the integer that occurred an odd number times.

Sample Input

3
1 1 2

Sample Output

2