6739: 找不同
[Creator : ]
Description
Give an odd number $n\ (1 \leq n \leq 10,000,001)$
Given you an array which have $n$ numbers : a[1] a[2] a[3] ... a[n]. They are positive num.
There are $n/2$ numbers which appear twice and only one number appears once.
Now you should tell me the number which appears only once.
Given you an array which have $n$ numbers : a[1] a[2] a[3] ... a[n]. They are positive num.
There are $n/2$ numbers which appear twice and only one number appears once.
Now you should tell me the number which appears only once.
Input
There are several test cases end with EOF.
The first line there is a integer $n$.
Then the $2$-nd line there are n integer a[1],a[2],...,a[n].
The first line there is a integer $n$.
Then the $2$-nd line there are n integer a[1],a[2],...,a[n].
Output
For each case, output the number which appears only once.
Sample 1 Input
7
3 2 7 2 1 7 3
1
7
11
1 1 2 2 3 3 4 4 5 5 9
Sample 1 Output
1
7
9