Squares - 2

In the white square $n$ times the same operation was performed: one of the smallest white squares was divided into $4$ identical squares and $2$ of them were painted black. For a given $n$ calculate how many percents of the area takes the black figure.

Input

One integer $n(1\le n\le 100)$.

Output

Print the area of the black figure in percents, rounded to $5$ decimal digits.

Examples