import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(),sum = -1;
        double Sn = 0;
        for (int i = 0,j = 1; i < n; i++,j++) {
            sum *= (-1);
            Sn += (1.0/j)*sum;
        }
        System.out.printf("%.4f",Sn);
    }
}