import java.util.*;
import java.text.*;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int num = sc.nextInt();
		int count = 0;
		int a = 0;

		for(int i = 1; i <= num; i++){
			a = i%2;
			if(a == 1){
				count+=1;
			}
		}
		double prob = (double)count/num;
		System.out.println(prob);

	}
}
/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