name the common serving line of neunkirchen hauptbahnhof and saarbrücken hauptbahnhof ?
SELECT DISTINCT var_uri where brack_open dbr_Neunkirchen_Hauptbahnhof dbo_servingRailwayLine var_uri sep_dot dbr_Saarbrücken_Hauptbahnhof dbo_servingRailwayLine var_uri brack_close