PROGRAMMING:Calculation of water charges by sections
In order to encourage the residents to save water, the water company adopts the method of pricing according to the water consumption step by step. The water fee y (yuan) paid by the residents is 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 a nonnegative real number x on one line.
###Output format:
Output the water charge to be paid in one line, accurate to 2 decimal places.
If the input x is negative, input data error! Is output!.
###Input example:
```in
twelve
```
###Output example:
```out
sixteen
```
###Input example:
```in
sixteen
```
###Output example:
```out
twenty-two point five zero
```
###Input example:
```in
-10
```
###Output example:
```out
Input Data error!
```
answer：If there is no answer, please comment
###Input format:
The input gives a nonnegative real number x on one line.
###Output format:
Output the water charge to be paid in one line, accurate to 2 decimal places.
If the input x is negative, input data error! Is output!.
###Input example:
```in
twelve
```
###Output example:
```out
sixteen
```
###Input example:
```in
sixteen
```
###Output example:
```out
twenty-two point five zero
```
###Input example:
```in
-10
```
###Output example:
```out
Input Data error!
```
answer：If there is no answer, please comment