import java.util.*;
 
public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    try {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } finally {
      sc.close();
    }
  }
} import java.util.*; util.* java public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    try {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } finally {
      sc.close();
    }
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    try {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } finally {
      sc.close();
    }
  } main {
    Scanner sc = new Scanner(System.in);
    try {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } finally {
      sc.close();
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) try {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } finally {
      sc.close();
    } {
      sc.close();
    } sc.close() sc.close sc {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } double n = sc.nextDouble(); n sc.nextDouble() sc.nextDouble sc double ans = Math.pow(n / 3, 3); ans Math.pow(n / 3, 3) Math.pow Math n / 3 n 3 3 System.out.printf("%f\n", ans) System.out.printf System.out System System.out "%f\n" ans String[] args args public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    try {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } finally {
      sc.close();
    }
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    try {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } finally {
      sc.close();
    }
  }
} Main
import java.util.*;
 
public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    try {
      double n = sc.nextDouble();
      double ans = Math.pow(n / 3, 3);
      System.out.printf("%f\n", ans);
    } finally {
      sc.close();
    }
  }
}