function f($)
  dim $h,$c,$o,$t
  $f=ubound($)
  for $c=0 to $f
      for $h=$c+1 to $f
	 $t = a+$[$c]+$[$h]+a
         if len($t)=2+2*len(join($,""))/($f+1)
              $o=$o+$t+$[$h]+$[$c]
         endif
      next
   next
  for each $ in split($o,a)
    $h=ubound(split($o,$))
    if $h>$t
      $t=$h
      $f=$
    ;endif
  ;next
endfunction