import java.util.*;

class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    double N = sc.nextDouble();

    double a = N%2;
    double b;

    if(a == 0){
       b = N/(2*N);
    }
    else{
       b = (N+1)/(2*N);
    }
    
    System.out.println(String.format("%.10f",b));

  }
}
/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