%g=("a"=>4,       "b"=>3,
  "c"=> 2,        "d"=>1,
    "f"=>0,       "+"=>
     1/3 ,        "-"=>
     -1/3);       while
     (<>){        chomp;
    next          unless
   m/^([abcdf])([+-])?$/;
                  $n+=1;
                  $t+=
                  $g{$1};
                m/(a\+|f-)/
               or $t+=$g{$2};}
              print($t/$n,"\n");