WineProblem

A large group of friends from the town of Nocillis visit the vineyards of Apan to taste wines. The vineyards produce many fine wines and the friends decide to buy as many as 3 bottles of wine each if they are available to purchase. Unfortunately, the vineyards of Apan have a peculiar restriction that they can not sell more than one bottle of the same wine. So the vineyards come up with the following scheme: They ask each person to write down a list of up to 10 wines that they enjoyed and would be happy buying. With this information, please help the vineyards maximize the number of wines that they can sell to the group of friends.