Square#8665

Square

1 second

64 megabytes

Easy

Kostya was so fascinated by geometry that he began drawing circles everywhere. One day, he drew a square with a side length of $a$ . From each vertex of the square, he drew a circle with a radius of $a$ , forming a total of 4 circles. This created a shape inside the square that looked like a rounded square. To challenge his friends' understanding of geometry, Kostya asked them to calculate the area of this "rounded square".

Input

The side length of the square is given as a real number $a$ .

Output

Print the area of the shape, rounded to three decimal places.

Examples

Example 1

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