import java.util.Scanner;

class Main{
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        if(a%2==0){
            System.out.println("0.5000000000");
        }else{
            int shou = a / 2;
            System.out.println((double)(a-shou)/a);
        }

    }
}
/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