def get_sorted_array(arr):
    size = len(arr)
    for i in range(size):
        for j in range(i+1, size):
            if arr[i] > arr[j]:
                arr[i], arr[j] = arr[j], arr[i]
    return arr

def solve(N, A, B):
    A = get_sorted_array(arr=A)
    B = get_sorted_array(arr=B)
    for i in range(len(A)):
        if A[i] != B[i]:
            return A[i]
    return -1

N = input()
A = map(int, raw_input().split())
B = map(int, raw_input().split())

out = solve(N, A, B)
print(out_)