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.
hide comments
julkas:
20161206 09:24:29
One pass. O(N). 

asgupta_spoj:
20161203 20:14:53
easy question


epsilonalpha:
20161127 00:36:55
Accepted in one go! Did a similar question back on HackerRank. 

venky1001:
20161112 18:33:20
TLE in O(n) even after using FastReader in JAVA :(


miranikaran:
20161101 02:24:44
TLE even for O(n) solution...wtf? 

sas1905:
20161028 19:16:57
O(nlogn+n) gives AC.0(n^2) TLE.Nice question. 

sumit_saurav:
20161007 09:01:23
Use ios_base::sync_with_stdio(false);


kr123:
20161005 21:45:45
Logic that gave TLE in python got accepted in C++. Can anyone please explain why this happens? 

rahadiankputra:
20161003 13:00:18
someone mentioned XOR, and golly, never taught about that!


Vipin:
20160913 16:33:00
CPP users using cin and cout use

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