判断ip地址是否合法

ip = input()
if ip[0] == '.'&nbs***bsp;ip[-1] == '.':
    print('invalid')
else:
    flag = True
    for i in range(len(ip)):
        if ip[i] != '.' and (ip[i]< '0'&nbs***bsp;ip[i] > '9'):
            flag = False
            print('invalid')
            break
        elif ip[i] == '.':
            if ip[i+1] == '.':
                flag = False
                print('invalid')
                break
    if flag:
        iplist = ip.split('.')
        if len(iplist) != 4:
            print('invalid')
        else:
            flag = True
            for j in iplist:
                if j[0] == '0' and len(j) > 1:
                    flag = False
                    print('invalid')
                    break
                elif int(j) < 0&nbs***bsp;int(j) > 255:
                    flag = False
                    print('invalid')
                    break
            if flag:
                iplist = [int(i) for i in iplist]
                if (iplist[0] >= 1 and iplist[0] < 126)&nbs***bsp;\
                (iplist[0] == 126 and iplist[1] == 0 and iplist[2] == 0 and iplist[3] == 0):
                    print('A_address')
                elif iplist[0] >= 128 and iplist[0] < 192:
                    print('B_address')
                elif iplist[0] >= 192 and iplist[0] < 224:
                    print('C_address')
                else:
                    print('other')