function a($b)
    dim $c,$d,$
    $d=join(split($b,_),$)
    $=1
    while $d
        $c=$d
        $d=right($d,~)
        $=$+($d<'/')
        $a=$a+50*(2*($c<'/'|$*($c>'/'&$c<_))|$*($c>_))
        $=$c<'/'
    loop
    $a=$a/($b^)
endfunction