import java.util.*;
import java.math.BigDecimal;

public class Main{
  public static void main (String args[]){
    Scanner sc = new Scanner(System.in);
    int num = sc.nextInt();
    double odds = 0;
    
    if(num%2 == 0){
      odds = (double) 0.5;
    } else {
      int numHalf = (num/2) + 1;
    odds = (double) numHalf/num;
    }
    System.out.println(odds);
  }
}
/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