import java.util.*;

public class Main {
	public  static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	double a = sc.nextInt();
	double b = 1/a;
	double c = Math.ceil(a/2);
	double d = b * c;

	System.out.println( d );
	}
}
/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