#include <bits/stdc++.h>
using namespace std;
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
 
    int N;
    cin >> N;
    string SS, SK, SH;
    cin >> SS >> SK >> SH;
 
    string S = SS;
    int scoreS = 0, scoreK = 0, scoreH = 0;
 
    for (int i = 0; i < N; i++) {
        if (S[i] == SS[i]) scoreS++;
        if (S[i] == SK[i]) scoreK++;
        if (S[i] == SH[i]) scoreH++;
    }
 
    auto check = [&](int a, int b, int c) {
        return (a > b && b > c);
    };
 
    if (check(scoreS, scoreK, scoreH)) {
        cout << S << "\n";
        return 0;
    }
 
    // 여러 자리를 고쳐야 할 수도 있으니 전체 탐색
    for (int i = 0; i < N; i++) {
        int oldS = (S[i] == SS[i]);
        int oldK = (S[i] == SK[i]);
        int oldH = (S[i] == SH[i]);
 
        // 후보 1: 고돌이 답 채택 (단, 한돌이는 틀리게)
        if (SK[i] != SH[i]) {
            int tmpS = scoreS - oldS + (SK[i] == SS[i]);
            int tmpK = scoreK - oldK + 1;
            int tmpH = scoreH - oldH + (SK[i] == SH[i] ? 1 : 0);
 
            if (tmpS > tmpK && tmpK > tmpH) {
                S[i] = SK[i];
                cout << S << "\n";
                return 0;
            }
 
            // 일단 바꿔서 점수 저장
            scoreS = tmpS;
            scoreK = tmpK;
            scoreH = tmpH;
            S[i] = SK[i];
        }
 
        // 후보 2: 셋 다 틀리게 (제3 문자 선택)
        if (!check(scoreS, scoreK, scoreH)) {
            int tmpS = scoreS - (S[i] == SS[i]);
            int tmpK = scoreK - (S[i] == SK[i]);
            int tmpH = scoreH - (S[i] == SH[i]);
            if (check(tmpS, tmpK, tmpH)) {
                for (char c = 'a'; c <= 'z'; c++) {
                    if (c != SS[i] && c != SK[i] && c != SH[i]) {
                        S[i] = c;
                        break;
                    }
                }
                cout << S << "\n";
                return 0;
            }
        }
    }
 
    if (check(scoreS, scoreK, scoreH)) {
        cout << S << "\n";
    } else {
        cout << -1 << "\n";
    }
    return 0;
}

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