OLOLO  Onotole needs your help
Onotole has a lot of pyani. Each pyani has a number, writing on it. Pyanis with equal numbers are indistinguishable. Onotole knows everything, so, he knows that each pyani appeared twice, and only one pyani is unique. He wants to get вздръжни эффект, and he needs the unique pyani. Given the list of pyanis denote which one of them appeared once (it is guaranteed that other pyanis appeared twice). 
Input
First line of input contains number of pyanis N <= 500 000. Next N lines contain a single positive integer 1 <= Pi <= 10^9.
Output
Output one positive integer on pyani, which appeared once.
Example
Input:
3
1
8
1
Output: 8
Onotole has found not optimal AC algorithms, so all solutions will be rejudged. He is watching you.
hide comments
rahul11197:
20190320 13:14:34
use XOR, good one


itzsowvik:
20190212 13:46:14
ios_base::sync_with_stdio(false);


roopammishra:
20190109 10:56:49
Sort then find!!:) 

Lucky Rathore:
20181222 07:11:33
on using "cin" its time limit exceed and on "scan" it shows AC... its crazy 

namannimmo:
20181219 17:06:18
the concept of taking xor of all the elements will be used!!


rohitnarayan:
20180825 14:16:25
Xor and scanf works good!! 

pavanjupalli:
20180823 16:11:38
easy problem


puneetgargmnc:
20180812 16:30:09
Just use Fast I/O n u will get AC 

anupamshah:
20180704 13:29:43
A very nice problem .!


masterchef2209:
20180703 21:13:45
never realised XOR has such a cool use, good one 
Added by:  Efim 
Date:  20101104 
Time limit:  0.134s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 