import java.util.Scanner;

 class Main{
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    //"1~100までの整数を入力してください
  int N = scanner.nextInt();
    if(N % 2 ==0) {
      System.out.println((double)1/2);
    }else{
      System.out.println((double)(N+1)/2/N);
    }
  }
  }
/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