import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception{
		Scanner scn = new Scanner(System.in);
		double L = scn.nextDouble();
		double x = L/3;
      	System.out.println(x*x*x);
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args) throws Exception{
		Scanner scn = new Scanner(System.in);
		double L = scn.nextDouble();
		double x = L/3;
      	System.out.println(x*x*x);
	}
} Main public static void main(String[] args) throws Exception{
		Scanner scn = new Scanner(System.in);
		double L = scn.nextDouble();
		double x = L/3;
      	System.out.println(x*x*x);
	} main {
		Scanner scn = new Scanner(System.in);
		double L = scn.nextDouble();
		double x = L/3;
      	System.out.println(x*x*x);
	} Scanner scn = new Scanner(System.in); scn new Scanner(System.in) double L = scn.nextDouble(); L scn.nextDouble() scn.nextDouble scn double x = L/3; x L/3 L 3 System.out.println(x*x*x) System.out.println System.out System System.out x*x*x x*x*x x x x String[] args args public class Main {
	public static void main(String[] args) throws Exception{
		Scanner scn = new Scanner(System.in);
		double L = scn.nextDouble();
		double x = L/3;
      	System.out.println(x*x*x);
	}
} public class Main {
	public static void main(String[] args) throws Exception{
		Scanner scn = new Scanner(System.in);
		double L = scn.nextDouble();
		double x = L/3;
      	System.out.println(x*x*x);
	}
} Main
import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception{
		Scanner scn = new Scanner(System.in);
		double L = scn.nextDouble();
		double x = L/3;
      	System.out.println(x*x*x);
	}
}