Description

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

Sample Output

#include<iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;int a[8][156];int main(){    int n,i,j;    char s[8];    while(~scanf("%d",&n))    {        memset(a,0,sizeof(a));        for(i=0;i<(2*n)-1;i++)        {            scanf("%s",s);            for(j=0;j<7;j++)            {                a[j][s[j]]++;//j代表第幾位,a[i][j]表示的是第幾位的字符出現次數            }        }        for(i=0;i<7;i++)        {            for(j=0;j<156;j++)            {                if(a[i][j]%2==1)//遍歷輸出就可以了                {                    PRintf("%c",j);                   break;                }            }        }        printf("/n");    }    return 0;}