@staticmethod
def a():
    l = [int(l) for l in sys.stdin.readline().split()]
    l.sort()
    print((l[2] if (l[0] == l[1]) else l[0]))
@staticmethod
def a():
    l = [int(l) for l in sys.stdin.readline().split()]
    l.sort()
    print((l[2] if (l[0] == l[1]) else l[0]))