import pprint, bisect, time, functools, collections, copy, heapq, math, string, sys, re
from typing import List, Any
import itertools as it
import numpy as np
import scipy as sc

ts = time.time()


# --end--#
class Funcinput:
    def __init__(self):
        pass

    def InputStrList(self, N):
        li = [input() for _ in range(N)]
        return li

    def InputStrMultiple(self):
        return sys.stdin.readline().rstrip().split()

    def InputIntMultiple(self):
        return map(int, input().split())

    def InputIntList(self):
        return list(map(int, input().split()))

    def InputIntListCycle(self, N):
        li = [list(map(int, input().split())) for _ in range(N)]
        return (li)

    def InputStrListCycle(self, N):
        li = [input().split() for _ in range(N)]
        return li

    def InputStrColumn(self):
        x = input()
        li = []
        for i in range(len(x)):
            li.append(x[i])
        return li


class ListFunc:

    def __init__(self):
        pass

    def UniqueListInt(self, R):
        li = [list(map(int, input().split())) for _ in range(R)]
        li_uniq = list(set(li))
        return li_uniq

    def UniqueListStrSingle(self, R):
        li = [input() for _ in range(R)]
        li_uniq = list(set(li))
        return li_uniq

    def UniqueListStrMultiple(self, R):
        li = [sys.stdin.readline().rstrip().split() for _ in range(R)]
        li_uniq = list(set(li))
        return li_uniq

    def DoubledList(self, l):
        l1 = l.copy()
        ret = [None] * (len(l) + len(l1))
        ret[::2] = l
        ret[1::2] = l1
        return ret

    def SplitListDouble(self, l):
        x, y = [], []
        x = l[::2]
        y = l[1::2]
        return x, y


def str_to_int_sort(str_, x):  # 0 = normal, 1 = reverse. unaccept alphabet
    if x == 0:
        st = sorted(str_)
        st = ''.join(map(str, st))
        return int(st)
    elif x == 1:
        st = list(str_)
        st.sort(reverse=True)
        st = ''.join(map(str, st))
        return int(st)
    else:
        print(-1)


def make_divisors(x):
    l_div, u_div = [], []
    i = 1
    while i * i <= x:
        if x % i == 0:
            l_div.append(i)
            if i != x // i:
                u_div.append((x // 1))
        i += 1
    return l_div + u_div[::-1]


def reverse(S):
    X = []
    str = ""
    for i in range(len(S)):
        i += 1
        X.append(S[-i])

    return str.join(X)


def permutation(l):
    return list(it.permutations(l))


def combination(l, p):
    return list(it.combinations(l, p))


def getNearestNum(l, n):
    idx = np.abs(np.asarray(l) - n).argmin()
    return l[idx]


def ketanowa(n):
    x = sum(list(map(int, str(n))))
    return x


# --instance--#
fni = Funcinput()
fnl = ListFunc()
out = print


# --solve--#
def solve():
    n = int(input())
    a = list(input().split())
    b = list(input().split())

    for i in a:
        if i in b:
            continue
        else:
            print(i)
            exit()

solve()
# te = time.time()
# print(te-ts)