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
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


smtcoder:
20160821 11:32:27
Really a very good concept in this question..looks like a very very easy problem but time limit forces you to use that concept..learnt something new from it :)


ankit1cool:
20160821 08:53:06
good question learnt a new concept


madhavgaba:
20160820 16:00:23
Tutorial worthy ques... AC in one go Last edit: 20160820 16:00:48 

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