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

S = set([0, 1, 2, 3])

if a==b==c:
    print(a)
elif a!=b and b!=c and c!=a:
    S.discard(a)
    S.discard(b)
    S.discard(c)
    for s in S:
        print(s)
        exit()
else:
    if a==b:
        print(c)
    elif b==c:
        print(a)
    elif c==a:
        print(b)