from itertools import *
def f(x, y, z):
    return ((not(x)) and y and z) or ((not(x)) and (not(z)))
table = [(0, 0, 0), (1, 0, 0), (1, 1, 0)]
for p in permutations('xyz'):
    if [f(**dict(zip(p, r))) for r in table] == [1, 1, 1]:
        print(p)