A guy is called upon by the king.
The king wants to throw a party, but he doesn't have any wine left.
The guy promises the king that he will deliver as many bottles as he can.
He will go on foot, for the 6 mile distance, to bring the bottles.
He can carry only 6 bottles at a time and has only 18 bottles at home, but he needs to drink 1 bottle each mile on the way to the castle and also 1 on the way back home.
What is the maximum number of bottles the guy can deliver and how many miles will he have travelled?