#include <bits/stdc++.h>
using namespace std;
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
 
    int N;
    cin >> N;
    string S_S, S_K, S_H;
    cin >> S_S >> S_K >> S_H;
 
    string S = S_S; // 처음엔 숭돌이 답안
 
    // 초기 점수 계산
    int scoreS = 0, scoreK = 0, scoreH = 0;
    for (int i = 0; i < N; i++) {
        if (S[i] == S_S[i]) scoreS++;
        if (S[i] == S_K[i]) scoreK++;
        if (S[i] == S_H[i]) scoreH++;
    }
 
    // 바로 조건을 만족하면 출력
    if (scoreS > scoreK && scoreK > scoreH) {
        cout << S << "\n";
        return 0;
    }
 
    // 한 위치를 바꿔보면서 확인
    for (int i = 0; i < N; i++) {
        char orig = S[i];
        // 후보: S_K[i], S_H[i], 또는 아무도 아닌 다른 문자
        vector<char> candidates = {S_K[i], S_H[i]};
        for (char c = 'a'; c <= 'z'; c++) {
            if (c != S_S[i] && c != S_K[i] && c != S_H[i]) {
                candidates.push_back(c);
                break; // 하나만 있으면 충분
            }
        }
 
        for (char cand : candidates) {
            S[i] = cand;
 
            int s = 0, k = 0, h = 0;
            for (int j = 0; j < N; j++) {
                if (S[j] == S_S[j]) s++;
                if (S[j] == S_K[j]) k++;
                if (S[j] == S_H[j]) h++;
            }
 
            if (s > k && k > h) {
                cout << S << "\n";
                return 0;
            }
        }
 
        S[i] = orig; // 복원
    }
 
    cout << -1 << "\n";
    return 0;
}

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