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Problems

Equation - 1

Equation - 1

Time limit 1 second
Memory limit 128 MiB

For given positive integer k solve the equation

prb8673.gif

It is known that equation has one root.

Input data

One positive integer k (k10^9).

Output data

Print the single root of the equation with 4 decimal digits.

Examples

Input example #1
2
Output example #1
1.5723