And immediately after posting...realized I could have shaved more..

125
 Code:
function a($)
$a = Ro, Sp, Pa, Li, Sc

$a = (AScan($a, Left($,2)) + 5 - AScan($a, Left(Split($,",")[1],2))) mod 5

$a = IIf($a>2, 2, $a>0*1)
endfunction