Four Circles#269
Four circles are mutually tangent to one another as shown in the diagram. If the radii of the three larger circles are , , and , what is the radius of the fourth circle?
The only line contains three integers , , (1 \leq a, b, c \leq 1000) — the radii of the larger circles.
Print the radius of the fourth, smallest, circle as a real number rounded to digits after the decimal point.
Example 1