case structure with binary number as case

Hi, i wanna to do a case structure with binary as case instead of true and false. I did it in following way.

The problem that i have now is that

10 - available

01 - not available

11 - booked

when i reach the not available stage, i wan it jump to the avalaible case instead of booked stage after my sensor is detecting nothing. Can someone help me with better idea? thank you very much.