题解 | #判断两个IP是否属于同一子网#

import sys

def ipgood(ip):
    iplist = ip.split('.')
    if len(iplist)!=4 :
        return False

    twostr = ''
    for i in iplist:
        if not i.isdigit():
            return False
        if int(i)>255 or int(i)<0:
            return False
        intwo = bin(int(i))[2:]
        twostr += intwo.zfill(8)
    
    return twostr

def maskgood(mask):

    masklist = mask.split('.')
    if len(masklist)!=4:
        return False
    twostr = ''
    for i in masklist:
        if not i.isdigit():
            return False
        if int(i)>255 or int(i)<0:
            return False
        intwo = bin(int(i))[2:]
        twostr += intwo.zfill(8)
    is_one=1
    if twostr[0]==0:
        return False
    for i in twostr:
        if i=='0':
            is_one=0
        if is_one==0 and i=='1':
            return False
    if is_one:
        return False
    
    return twostr

mask = input().strip()
ip1 = input().strip()
ip2 = input().strip()

ip1 = ipgood(ip1)
ip2 = ipgood(ip2)
mask = maskgood(mask)

if not (ip1 and ip2 and mask):
    print('1')
else:
    ip1 = int('0b'+ip1,2)
    ip2 = int('0b'+ip2,2)
    mask = int('0b'+mask,2)

    maip1 = mask&ip1
    maip2 = mask&ip2
    if maip1 == maip2:
        print('0')
    else:
        print(2)