Count formula required

I currently have a formula that counts the letter 'S' when placed in a grid COUNTIF(A4:D4,"S")

The new formula I require needs to do the same accept it needs to convert to hours. I know that if I put *12 after the bracket it will multiply the S by 12 giving a toatl but I need the numeric to change.

ie if i put S4 in A4 and S6 in A5 i need it to recognise these numbers and give a total at the end of 10

so formula i need is S(any number) in say A4, S(any number) in say A5, Total = (numbers added)

Any questions if I havent explained it enough please post