a,b,c = map(int,input().split())
box = [0,1,2,3]

if a==b==c:
    print(a)

elif a != b and b != c and a != c :
    for s in box:
        if s not in [a,b,c]:
            print(s)

else:
    if a==b:
        print(c)
    elif b==c:
        print(a)
    else:
        print(b)