find a flight from charlotte to las vegas that stop in st. louis that serve dinner and i want to find the airline for this flight 
return flights ;return #1 from charlotte ;return #2 to  las vegas ;return #3 with  stop in st. louis ;return #4 that  serve dinner ;return airlines of #5 ;return #5 ,  #6
['select', 'filter', 'filter', 'filter', 'filter', 'project', 'union']