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