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.
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mawr_ty:
20200619 19:44:46
AC in one go.Used HashSet in Java :) 

abhishek_251:
20200419 20:09:48
use xor only and no need to maintain an array..... got AC without using fast i/o. 

subhamm99:
20190617 22:07:07
got ac..just use scanf instead of cin if your logic is correct to avoid tle.. 

anand_undavia:
20190617 21:53:16
Onotole hates Java. :P


sarthak_1998:
20190520 17:40:16
Got AC only after using ios::sync_with_stdio(false); cin.tie(0); cout.tie(0) 

aj_254:
20190506 10:33:09
ez in python just for output stdout.write and for input use stdin.readline and main logic of program is by xor.....solvable in python ..so do not make excuses 

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 
Added by:  Efim 
Date:  20101104 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 