java

import java.util.Scanner;
import java.text.DecimalFormat;
import java.lang.Math;
public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        double sum=0;
        for(int i=1;i<=n;i++){
           sum = sum+ Math.pow(-1,i+1)/i;
        }
        DecimalFormat res = new DecimalFormat("0.000");
        System.out.println(res.format((double)sum));
    }
}