题解 | #判断两个IP是否属于同一子网#

mask_ip = [int(i) for i in input().split('.')]
ip1 = [int(i) for i in input().split('.')]
ip2 = [int(i) for i in input().split('.')]
flag = 0
for i in mask_ip + ip1 + ip2:
    if i < 0 or i > 255:
        flag = 1
        break
if flag != 1:
    # 先判断子网掩码是否合法
    mask_ip1 = ['0'*(8-len(bin(i)[2:]))+bin(i)[2:] for i in mask_ip]
    mask_ip2 = ''.join(mask_ip1)
    if set(mask_ip2) in ({'0'},{'1'}) or '01' in mask_ip2:
        flag = 1
    else:
        for i in range(4):
            if ip1[i]&mask_ip[i] != ip2[i]&mask_ip[i]:flag = 2
print(flag)