import java.util.Scanner;

class Main
{
    public static void main(String[] args)
    {
      //入力
      Scanner sc = new Scanner(System.in);
      int n = sc.nextInt();
      
      //計算
      double p = 0;
      int sum = 0;
      for(int i=1;i<=n;i++) {
        if(i%2!=0) sum += 1;
      }
      p=(double)sum/n;
      
      //出力
      System.out.println(p);
      
    }
      
}


/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