a,b,c = map(int,input().split())
if a == b and b == c:
    print(a)
elif a != b and a != c and b != c:
    print(6-a-b-c)
else:
    L = [a,b,c]
    L.sort()
    if L[0] == L[1]:
        print(L[2])
    else:
        print(L[0])