Problem statement for ruby code

grocerycalculator.txt

## Sale Discount for a store

At the grocery store items are sold by quantity. For example Milk costs $3.97. However sometimes there is a sale and then consumers can buy n items for the price of one. 

This week the pricing table at the local grocery store looks like this

```
Item     Unit price        Sale price
--------------------------------------
Milk      $3.97            2 for $5.00
Bread     $2.17            3 for $6.00
Banana    $0.99
Apple     $0.89
```

At the cash counter the items are accepted in any order. 
So at the cash counter the order of items can be Bread, Banana, Milk, Apple, Bread and then Milk. Notice that quantity of the Milk is 2 and this week there is a sale on Milk if 2 milk is purchased. So the price applied for milk should be $5.00.

Note that if the user buys three milk then 

1. for the first two milk user should pay the sale price
2. for the third milk user should pay the unit price.
3. So the total price for three milk will be $5.00 + $3.97 = $8.97

### Task

Task is to build a ruby program which when executed would ask user to list all the items purchased in any order. 
Once user has listed all the items then print the total cost. 
You need to build solution for the given items and you do not need to worry about items which would be added in future -- in other words the pricing table is static.

``` 
$ ruby price_calculator.rb
Please enter all the items purchased separated by a comma
milk,milk, bread,banana,bread,bread,bread,milk,apple

Item     Quantity      Price
--------------------------------------
Milk      3            $8.97
Bread     4            $8.17
Apple     1            $0.89
Banana    1            $0.99  

Total price : $19.02
You saved $3.45 today.

```