a, b, c =list(map(int,input().split()))



if int(a) == int(b):

  print(c)

elif int(a) == int(c):

  print(b)

elif int(b) == int(c):

  print(a)
a, b, c = list(map(int,input().split()))



if int(a) == int(b):

  print(c)

if int(a) == int(c):

  print(b)

if int(b) == int(c):

  print(a)
a, b, c = list(map(int, input().split()))
if int(a) == int(b):
    print(c)
elif int(a) == int(c):
    print(b)
elif int(b) == int(c):
    print(a)

a, b, c = list(map(int, input().split()))
if int(a) == int(b):
    print(c)
if int(a) == int(c):
    print(b)
if int(b) == int(c):
    print(a)

-elif int(a) == int(c): +if int(a) == int(c): -elif int(b) == int(c): +if int(b) == int(c):