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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sayedathar11:
20160819 03:43:19
The time constraints of the problem makes it special other wise it is very trivial problem needed 2 attempts for That :) 

pratyush2311:
20160804 17:26:46
c++ users,use scanf and printf instead of cin and cout respectively. 

vaibhavahuja:
20160731 03:24:24
TLE every time in python. no matter what i use. 

syed_omar_ali_:
20160711 16:17:46
Easy One! My 50th. Happy Coding! 

at0000001:
20160704 20:24:25
Last edit: 20160704 20:25:07 

iharsh234:
20160701 10:57:06
can you check your input file please,Is there a blank line between two number?


suraj:
20160615 00:14:00
use scanf


ianand:
20160527 16:28:17
Use fast IO for java


ianand:
20160527 16:26:46
Please


ragwave:
20160522 19:32:24
time limit is very strict so use scanf and printf! 
Added by:  Efim 
Date:  20101104 
Time limit:  0.134s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 