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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Timmy Jose:
20151212 16:04:40
@Sumit Suthar


Timmy Jose:
20151212 16:03:07
For all people, complaining, this is a simple but beautiful problem. It's a pretty simple one, but I love its requirement for one to think and figure out the simple way! Last edit: 20151212 16:06:27 

priyanshukm_17:
20151211 12:48:34
Thank u @Abishek yr suggestion for fast io worked 

gibibyte:
20151122 18:44:32
use scanf to read values in c++ 

sumit suthar:
20151111 16:02:51
Just XOR... :) 

dk619:
20151028 23:07:32
If using Sort method use Scanf instead of CIN. 

shivam:
20151010 18:14:28
if using cin or cout,set sync_with_stdio(false);


nap11:
20151007 16:27:05
is this possible in java? 

DeviSree:
20150926 18:03:58
same sol TLE in python anyway nice question 

Sarthak Munshi:
20150920 13:17:29
ridiculous problem statement ! 
Added by:  Efim 
Date:  20101104 
Time limit:  0.134s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 