import sys
input = sys.stdin.readline
 
N = int(input())
SS = input().strip()
SK = input().strip()
SH = input().strip()
 
ans = []
scoreS = scoreK = scoreH = 0
 
for i in range(N):
    s, k, h = SS[i], SK[i], SH[i]
 
    if s == k == h:
        # 셋 다 같으면 -> 제3문자 (아무도 점수 안 받음)
        c = 'z' if s != 'z' else 'y'
 
    elif s == k and s != h:
        # 숭=고, 한 다름
        # 숭>고 관계 유지가 힘듦 -> 제3문자로 점수 안 줌
        c = 'z' if s != 'z' else 'y'
 
    elif s == h and s != k:
        # 숭=한, 고 다름
        # 여기서 고를 선택해 주면 고 점수만 +1 가능
        c = k
        scoreK += 1
 
    elif k == h and s != k:
        # 고=한, 숭 다름
        # 숭 선택 -> 숭만 점수
        c = s
        scoreS += 1
 
    else:
        # 셋 다 다름
        # 숭 선택 -> 숭 점수만
        c = s
        scoreS += 1
 
    ans.append(c)
 
# 최종 점수 계산
scoreS = sum(1 for i in range(N) if ans[i] == SS[i])
scoreK = sum(1 for i in range(N) if ans[i] == SK[i])
scoreH = sum(1 for i in range(N) if ans[i] == SH[i])
 
if scoreS > scoreK > scoreH:
    print("".join(ans))
else:
    print(-1)

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