Description

Read in $n$, compute the value of $S=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}+\dots+\frac{1}{n}$. Output the result left-aligned, retaining 10 decimal places.

Input Format

Input a number $n$.

Output Format

Output $S$.

6

0.6166666667

Hint

Data Range:
1 ≤ $n$ ≤ 100

Source

CodesOnline