Cindy has challenged Weiwei a simple question today, and Weiwei promises to give the answer before lunch break, or else he is going to buy lunch for Cindy. There are only 5 minutes left until lunch starts, but Weiwei still has no idea whatsoever about how to solve this problem. You, as Weiwei's best friend, are trying to help him find out the answer.
Weiwei is given a multiset of integers. Out of all integers, only one appeared an odd number of times, and all others have appeared an even number of times. What is the value of this integer?
The first line of input contains the integer .
Next lines: one integer , which is a number in the multiset.
Output one integer, the integer that occurred an odd number times.
5 3 3 18 4 4