import java.util.*;
public class Main {
        public static void main(String args[]){
          
        Scanner sc = new Scanner(System.in);
          
          //入力
          int L = sc.nextInt();
          
          double M = (double) L/3;
          
          //直方体の体積(最大)
          System.out.println(Math.pow(M,3));
        }
} import java.util.*; util.* java public class Main {
        public static void main(String args[]){
          
        Scanner sc = new Scanner(System.in);
          
          //入力
          int L = sc.nextInt();
          
          double M = (double) L/3;
          
          //直方体の体積(最大)
          System.out.println(Math.pow(M,3));
        }
} Main public static void main(String args[]){
          
        Scanner sc = new Scanner(System.in);
          
          //入力
          int L = sc.nextInt();
          
          double M = (double) L/3;
          
          //直方体の体積(最大)
          System.out.println(Math.pow(M,3));
        } main {
          
        Scanner sc = new Scanner(System.in);
          
          //入力
          int L = sc.nextInt();
          
          double M = (double) L/3;
          
          //直方体の体積(最大)
          System.out.println(Math.pow(M,3));
        } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int L = sc.nextInt(); L sc.nextInt() sc.nextInt sc double M = (double) L/3; M (double) L/3 (double) L 3 System.out.println(Math.pow(M,3)) System.out.println System.out System System.out Math.pow(M,3) Math.pow Math M 3 String args[] args public class Main {
        public static void main(String args[]){
          
        Scanner sc = new Scanner(System.in);
          
          //入力
          int L = sc.nextInt();
          
          double M = (double) L/3;
          
          //直方体の体積(最大)
          System.out.println(Math.pow(M,3));
        }
} public class Main {
        public static void main(String args[]){
          
        Scanner sc = new Scanner(System.in);
          
          //入力
          int L = sc.nextInt();
          
          double M = (double) L/3;
          
          //直方体の体積(最大)
          System.out.println(Math.pow(M,3));
        }
} Main
import java.util.*;
public class Main {
        public static void main(String args[]){
          
        Scanner sc = new Scanner(System.in);
          
          //入力
          int L = sc.nextInt();
          
          double M = (double) L/3;
          
          //直方体の体積(最大)
          System.out.println(Math.pow(M,3));
        }
}