Cabinet Switch advice

I have 3 speakers, al 16 ohm. My blackstar HT-5 amp can power 2 x 16 ohm or 1 x 16 ohm. It looks like this
AMP: 1 2 or 3
Cab: A B C

I would like to switch to this:
1: 1 to A and 2 to B
2: 1 to A and 3 to B
3: 3 To C

Can anybody help my, i think it could be done with a rotary switch.

Thanxs for any advice.