PROGRAMMING:Calculation of water charges by sections
In order to encourage the residents to save water, the water company adopts the method of step pricing according to the water consumption, and the residents should pay the water fee $$y $$(yuan) related to the monthly water consumption $$x $$(ton): when $$x $$does not exceed 15 tons, $$y = 4x / 3 $$; After exceeding, $$y = 2.5x-17.5 $$. Please write a program to calculate the water charge.
###Input format:
The input gives the nonnegative real number $$x $$in one line.
###Output format:
Output the water charge to be paid in one line, accurate to 2 decimal places.
###Input sample 1:
```in
twelve
```
###Output sample 1:
```out
sixteen
```
###Input example 2:
```
sixteen
```
###Output example 2:
```
twenty-two point five zero
```
answer：If there is no answer, please comment
###Input format:
The input gives the nonnegative real number $$x $$in one line.
###Output format:
Output the water charge to be paid in one line, accurate to 2 decimal places.
###Input sample 1:
```in
twelve
```
###Output sample 1:
```out
sixteen
```
###Input example 2:
```
sixteen
```
###Output example 2:
```
twenty-two point five zero
```
answer：If there is no answer, please comment