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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singhaljoy:
20170122 12:10:18
Use property of XOR, AC in 1 go!!! 

shantanu_sarin:
20170120 13:55:34
cin cout gives TLE


scorpion_ajay:
20170112 12:02:12
easiest till :p 

coder_with_a_h:
20170101 17:18:59
cin and cout gives TLE


vunnamtej:
20161229 18:11:31
@apurvgs thanks for your comment 

rohitkr2997:
20161229 14:06:25
ios_base::sync_with_stdio (false);cin.tie(0); as first statement of main function. Use property of x^x=0 and x^0=x.


hasan356:
20161228 07:12:40
AC in one go!!Use Xor 

apurvgs:
20161214 06:48:33
cin and cout gives TLE


rakeshgupta:
20161213 11:33:09
@julkas what is "and ... 5 L. BR.??". Sorry, but i am a beginner in python, so not so well in acronyms (if it is one). Last edit: 20161213 11:37:24 

julkas:
20161206 09:24:29
One pass. O(N). 
Added by:  Efim 
Date:  20101104 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 