Circumference of a Circular Running Track

Given the area \(A\) of a circular running track, your task is to compute its circumference. By geometry, the radius \(r\) of a circle is derived from its area by the formula \(r = \sqrt{\frac{A}{\pi}}\) and the circumference \(C\) is given by \(C = 2\pi r = 2\pi \sqrt{\frac{A}{\pi}}\). Compute \(C\) and output the result with exactly 6 decimal places.

inputFormat

A single integer (A) (where (1 \leq A \leq 10^{18})) representing the area of the circular track in square meters.

outputFormat

A single floating-point number representing the circumference of the track, printed to stdout with 6 decimal places.## sample

314

62.831853