PROGRAMMING:Finding the area of a circle

Input the radius r of the circle, calculate its area and output.
###Input format:
Enter a real number greater than zero without any additional characters.
###Output format:
Output the result directly. The result is a real number with 6 decimal places and no additional characters.
###Input example:
```in
one
```
###Output example:
```out
three point one four zero zero zero zero
```






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