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Intro to geometry - 1

Triangle

prb418

Given a triangle and a point inside it. Through this point draw a line parallel to the sides of the triangle. These lines form the three triangles within a given. Their area known. Find the area of original triangle.

Input

One line contains three real positive numbers S1, S2 and S3. All numbers do not exceed 1000.

Output

Print area of triangle with 8 digits after the decimal point.

Time limit 1 second
Memory limit 128 MiB
Input example #1
1.0 2.0 3.0
Output example #1
17.19150823