Working with multiple delimiters in a string

yes, 172.18.1.160 and 172.18.1.9 would be 255.255.255.0

so each of the three calculations would look like 255-abs(ip1-ip2)

I just don't know how to pull the proper numbers without splitting everything into columns

Some additional examples:

172.17.1.200 and 172.18.1.190 would yield 255.254.255.0
172.18.1.100 and 172.18.3.100 would yield 255.255.253.0