import sys

sys.setrecursionlimit(10 ** 7)


def get_list(ty=int):
    return list(map(ty, input().split()))


def get_int():
    return int(input())


def get_str():
    return input()


A, B, C = get_list()

if len({A, B, C}) == 1:
    print(A)
    exit(0)

from collections import defaultdict

d = defaultdict(int)
for x in [A, B, C]:
    d[x] += 1

if any(d[k] == 1 for k in d.keys()) and any(d[k] == 2 for k in d.keys()):
    print(max(k for k in d.keys() if d[k] == 1))
    exit(0)

print(list({0, 1, 2, 3} - {A, B, C})[0])