sub get_output {
         my ($source,$pair) = @_;
    
      my @output = ();
      my %done = ();
      foreach my $pr (@{$pair}){
         foreach my $sc (@{$source}){
                 next if ($pr <= $kn || $done{$sc});
                 push @output,$sc;  
                 $done{$sc} = 1;
          
         }
      }
    
      use Data::Dumper;
      print Dumper \@output;
      return @output;
    }