// iostream is too mainstream
#include <cstdio>
// bitch please
#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <iomanip>
#define dibs reserve
#define OVER9000 1234567890
#define patkan 9
#define tisic 47
#define soclose 10e-7
#define ALL_THE(CAKE,LIE) for(auto LIE =CAKE.begin(); LIE != CAKE.end(); LIE++)
#define chocolate win
#define ff first
#define ss second
#define abs(x) ((x < 0)?-(x):(x))
// mylittlepony
using namespace std;
	
	
int main() {
    cin.sync_with_stdio(0);
    int N;
    cin >> N;
    string a[3];
    cin >> a[0] >> a[1] >> a[2];
    for(int i =0; i < N; i++) {
    	if(a[0][i] == a[1][i]) {cout << a[0][i]; continue;}
    	if(a[1][i] == a[2][i]) {cout << a[1][i]; continue;}
    	cout << a[0][i];}
    cout << "\n";
    return 0;}
        
// look at my code
// my code is amazing