PROGRAMMING:4-4 input Apple grade and quantity, calculate and output AP

There are four grades of apples in 4-4 Apple Store: Grade I 5.50 yuan / kg, grade II 4.30 yuan / kg, grade III 3.00 yuan / kg and grade IV 2.50 yuan / kg. Using the switch statement to write a program, input the apple grade, quantity, output the amount of accounts payable. When the level of the input apple is not up to the requirements, "data error!" is output, Close the program.
###Input format:
For example: give the level and quantity in a line, separated by a space.
###Output format:
For example, the amount you should pay is XX Yuan.
###Input example:
Here is a set of inputs. For example:
```in
1 1
```
###Output example:
The corresponding output is given here. For example:
```out
five point five zero
```







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