import java.util.*;

public class Main {
    public static void main(String[] args){
        int N;
        Scanner sc = new Scanner(System.in);
        N = sc.nextInt();
        int cont = 0;
        for (int i=1; i<=N; i+=2){
            cont++;
        }
        System.out.printf("%.9f\n", cont*1.0/N);
    }
}

/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