8(один икс с count)

alph = 'ABCX'
answ = 0
for a in alph:
    for b in alph:
        for c in alph:
            for d in alph:
                for e in alph:
                    s = a + b + c + d + e
                    if s.count('X'):
                        answ += 1
print(answ)