IP Subnet Calculator Update

This is an update to my previous code submission. This one will calculate Class A, B and C addresses. I would like to thank flipmode for informing me that it is the last ip and not the first that is the network number. It takes a while to calculate Class A addresses since they are so large. So if you are calculating a Class A and it stops responding just let it go for a while and it will probably catch up. I also ran out of memory trying to calculate a Class A address so you might want to watch out there to. I appreciate comments so I can improve my work. Thank's