Error, please use a valid command (valid commands: 'quit' 'info' 'vertices' 'nodes ' 'remove ;' 'insert ;;;' 'route ;;' 'search ;;' [numbers can't be zero or less]) Error, vertex not found Error, please use a valid command (valid commands: 'quit' 'info' 'vertices' 'nodes ' 'remove ;' 'insert ;;;' 'route ;;' 'search ;;' [numbers can't be zero or less]) Error, vertex not found Error, vertex not found bB C d bB C d Aa bB d Aa C Aa C