---

from itertools import *

def f(x,y,z,w):
    return ((x==(not(y)))<=(not(w<=x))) or (not(z))

for a1,a2,a3,a4,a5 in product([0,1],repeat=5):
    tab=[(a1,0,1,0),(0,a2,a3,0),(a4,1,1,a5)]
    if len(tab)==len(set(tab)):
        for p in permutations("xyzw"):
            if [f(**dict(zip(p,r))) for r in tab] == [0,0,0]:
                print (p)