15 с отрезками

mx = 0
for l in range(40):
    for r in range(l, 40):
        f = True
        for x in range(-10, 50):
            if not ((((x >= 5) and (x <= 30)) == ((x >= 14) and (x <= 23))) <= (not ((x >= l) and (x <= r)))):
                f = False
        if f:
            mx = max(mx, r - l)
print(mx)