import java.util.Scanner;
public class Main {
	  public static void main(String[] args) {
	    Scanner sc = new Scanner(System.in);
	    int n = sc.nextInt();
	    double m = n;
	    if(m % 2 ==0) {
	      System.out.println(0.5);
	    } else {
	      System.out.println((m+1)/(2*m));
	    }
	  }
	}

/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