def ot(x, y): return [i for i in range(x, y + 1)]

P = ot(170, 540)
Q = ot(370, 830)

def f(x, A):
    return (x in P) <= ((( x in Q) and (x not in A)) <= (x not in P))


from tqdm import tqdm

min_A = 100**10
for x1 in tqdm(range(160, 840)):
    for x2 in range(x1 + 1, 840):
        A = ot(x1, x2)
        ok = True
        for x in range(160, 840):
            if not f(x, A):
                ok = False
                break

        if ok:
            min_A = min(min_A, len(A))

print(min_A / 10)#если .9, то округляем с большую сторону.