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