#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <cstring>
#include <algorithm>
using namespace std;
int n;
bool judge(string s1, string s2, string s3){
    reverse(s1.begin(), s1.end());
    bool flag = true;
    for(int i = 0; i < n; i++){
        if((((s2[i]-'0')+(s3[i]-'0'))-2*(s1[i]-'0'))%26 != 0){
            flag = false;
            break;
        }
    }
    return flag;
}
int main(){
    string s1, s2, s3;
    cin >> n;
    cin >> s1 >> s2 >> s3;
    if(judge(s1,s2, s3)){
        reverse(s1.begin(), s1.end());
        cout << s1 << endl;
    }
    else if(judge(s2,s1, s3)){
        reverse(s2.begin(), s2.end());
        cout << s2 << endl;
    }
    else if(judge(s3,s1, s2)){
        reverse(s3.begin(), s3.end());
        cout << s3 << endl;
    }
    return 0;
} 

//%26很重要

#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <cstring>
#include <algorithm>
using namespace std;

int main(){
    int n;
    char str[4][10005];
    cin >> n;
    int i;
    for (i = 0; i < 3; i++){
        cin >> str[i];
    }
    int len = strlen(str[1]);
    for(int j = 0; j < len/2; j++){
        char temp = str[0][j];
        str[0][j] = str[0][len-j-1];
        str[0][len-j-1] = temp;
    }
    cout << str[0] << endl;
    return 0;
} 

//速得20分垃圾方法