import java.util.*;
public class Main
{
	public static void main(String[] args)
    {
      	Scanner sc = new Scanner(System.in);
    	int n = sc.nextInt();
      	double prob = 0;
      	if(n % 2 == 0) prob = 0.5;
      	else{
        	prob = ((n + 1) / 2.0) / (double)n;
        }
      	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