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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bani_raheja:
20171229 16:07:26
what is the point of having such problems if you want people to use Fast I/O? :3 

sai__teja_01:
20171129 19:29:18
easy problem ,if ur facing TLE use scanf and printf instead cin and cout ,if ur using c++ 

hitesh87:
20171005 22:42:39
Learned to use xor.AC in many goes;p 

vishesh197:
20170923 17:22:15
just use xor as x^x=0 and x^0=x 

frobenius:
20170816 20:04:11
Unlike most other problems, do not put a newline at the end of your answer... it will count as wrong. 

bhawna_123:
20170704 07:56:34
For a=a^t ,it is giving segmentation fault if i take 'a' as an integer.Could anybody explain me why this is happening 

ramesh_961:
20170603 20:18:42
Use printf or scanf if you use c++ instead of cin and cout to avoid TLE!! 

shauryauppal:
20170602 14:00:48
use scanf or printf


ayushgupta1997:
20170528 11:00:10
EAsy man took the mistook array size as 10^5 instead of 5*10^5 costed me sigsev...use xor basics :) 

sagnik_66:
20170521 08:09:59
Easy! 
Added by:  Efim 
Date:  20101104 
Time limit:  0.134s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 