Alice bought a lot of pairs of socks yesterday. But when she went home, she found that she has lost one of them. Each sock has a name which contains exactly 7 charaters.

Alice wants to know which sock she has lost. Maybe you can help her.

Input

There are multiple cases. The first line containing an integer n (1 <= n <= 1000000) indicates that Alice bought n pairs of socks. For the following 2*n-1 lines, each line is a string with 7 charaters indicating the name of the socks that Alice took back.

Output

The name of the lost sock.

Sample Input

2

aabcdef

bzyxwvu

bzyxwvu

4

aqwerty

eas fgh

aqwerty

easdfgh

easdfgh

aqwerty

aqwerty

2

0x0abcd

0ABCDEF

0x0abcd

Sample Output

aabcdef

eas fgh

0ABCDEF

有2*n-1个袜子，叫你找出不能配对的那个袜子。

 

 

只有一个出现奇数次，答案就是它了：

#include<cstdio>

#include<cstdlib>

#include<iostream>

#include<cstring>

#include<memory.h>

using namespace std;

char s[],c;

int main()

{

    int n;

    while(~scanf("%d\n",&n)){

        for(int i=;i<=;i++) s[i]='\0';

        for(int i=;i<*n;i++){

            for(int j=;j<;j++){

                c=getchar();

                s[j]=s[j]^c;

            }

        }

        printf("%s",s);

    }

    return ;

}