Four Circles

prb269

Four circles are mutually tangent to one another as shown in the diagram. If the radiuses of the three larger circles are a, b and c, what is the radius of the fourth circle?

Specifications

Input

Single line contains three integers: a, b, c – the radiuses of the larger circles (1 ≤ a, b, c ≤ 1000).

Output

Output the radius (one real number accurate to 4 digits after decimal point) of the fourth, the smallest, circle.

Problem information

Time Limit: 0.1 seconds
Memory Limit: 64 MB
Balls for the passed test: 1
Complexity: 12% 29/33

Example

Example input

Sample 1
1 2 3

Sample 2
10 10 10

Example output

Sample 1
0.2609

Sample 2
1.5470

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