How to Split an IP range that is in one column to two columns for a database import ?

Customer has sent me a HUGE IP range list with x.x.x.x/xx but luckily they have also put in each row , as below

123.123.123.123-123.123.150.175

there are about 1000 rows like this

Want i want to do is have :

Column A the Start IP 123.123.123.123

Column B the End IP 123.123.150.175

only, then i can import to the customer account -

i am not an excel tech.. whats the easiest way to split these up

Thanks in Advance

EDIT - Solved - thank you to everyone and their replies - i have learnt something new and has saved me hours of work - Beers all round.