mivvka

# P2. Сумма: ближайшая
import numpy as np

n = int(input())
listA = np.array([int(x) for x in input().split()], int)
listB = np.array([int(x) for x in input().split()], int)
listA.sort()
listB.sort()

lenA = len(listA)

mivvka

inData = [5,8,8,4,5,2,6,3,7]
dubb = -1

for i in inData:
  if dubb>0 : break
  t=0
  for j in inData:
    if i==j : t=t+1
    if t>1 : dubb = j; break
print(dubb)