A bar is offering greatly reduced prices on their draft beer during their happy hour. (See above image for menu prices)

If a group of friends decide that they want to drink a total of $25$ liters, how much would it cost them(minimum)?

**Details and assumptions:**

- The bartender doesn't know mathematics, and he
gives:*always*

1) $\$2$ extra for ** each** $\dfrac 12$L drink you buy,

2) $\$4$ extra for ** each** $1$L drink you buy and,

3) $\$11$ extra for ** each** $2$L drink that you buy

For example, if you buy a $1$L drink and pay him $\$50$, he will give you $\$44$ instead of $\$40$.

You can buy

$\dfrac 12$L drink.*at most ten*You can buy drinks in natural numbers, i.e. you can't buy $12.5$ glasses of $2$L drink.

You have just got $\$50$ bills with you.