import java.util.*;



class Main
    {
        public static void main(String args[]) {
            Scanner in = new Scanner(System.in);
            double n = in.nextDouble();
            int t = (int)(n+1)/2;
            double r = t/n;
            System.out.printf("%.10f", r);


        }
    }


/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz