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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syed_tanveer:
20160222 16:49:44
cout and cin gave a TLE . :/ 

abc_c:
20160207 08:14:18
Amazing!!


hamcom1212:
20160126 07:15:01
I used hash map in c++ but get TLE .. :( 

prateekmathur1991:
20160112 11:34:50
Got AC with Java... :) Needs fast I/O though... 

dokz:
20160106 10:25:01
The problem seems to be impossible in C# \ Java. 

sarthak_8:
20160102 20:19:44
Why did not anybody do it with C++ Maps? 

Timmy Jose:
20151212 16:05:59
For people using C++ streams, try setting ios_base::sync_with_stdio(false) in your program before doing any input operations. This should help. 

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