use strict;
use warnings;
use diagnostics; # explain the warnings !

# guesses integet between two other integers
sub recuGuess($$){
   my($low,$high)=@_;
   my $mid=int (($low+$high)/2);
  
   print "is $mid low, high or correct? :";
   my $ans=<STDIN>;

   $ans=uc(substr($ans,0,1));
   if('C' eq $ans){
      print "thank you for playing\n";
   }elsif('L' eq $ans){
      &recuGuess($mid+1,$high);
   }elsif('H' eq $ans){
      &recuGuess($low,$mid-1);
   }else{
      print "bad input\n";
      &recuGuess($low,$high);
   } 	
}

recuGuess(1,40000);