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

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int L = sc.nextInt();
    sc.close();

    double ans = (double) (L * L * L) / (3d * 3d * 3d);
    System.out.println(BigDecimal.valueOf(ans).toPlainString());
  }
} import java.math.*; math.* java import java.util.*; util.* java public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int L = sc.nextInt();
    sc.close();

    double ans = (double) (L * L * L) / (3d * 3d * 3d);
    System.out.println(BigDecimal.valueOf(ans).toPlainString());
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int L = sc.nextInt();
    sc.close();

    double ans = (double) (L * L * L) / (3d * 3d * 3d);
    System.out.println(BigDecimal.valueOf(ans).toPlainString());
  } main {
    Scanner sc = new Scanner(System.in);
    int L = sc.nextInt();
    sc.close();

    double ans = (double) (L * L * L) / (3d * 3d * 3d);
    System.out.println(BigDecimal.valueOf(ans).toPlainString());
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int L = sc.nextInt(); L sc.nextInt() sc.nextInt sc sc.close() sc.close sc double ans = (double) (L * L * L) / (3d * 3d * 3d); ans (double) (L * L * L) / (3d * 3d * 3d) (double) (L * L * L) L * L * L L L L (3d * 3d * 3d) 3d * 3d * 3d 3d 3d 3d System.out.println(BigDecimal.valueOf(ans).toPlainString()) System.out.println System.out System System.out BigDecimal.valueOf(ans).toPlainString() BigDecimal.valueOf(ans).toPlainString BigDecimal.valueOf(ans) BigDecimal.valueOf BigDecimal ans String[] args args public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int L = sc.nextInt();
    sc.close();

    double ans = (double) (L * L * L) / (3d * 3d * 3d);
    System.out.println(BigDecimal.valueOf(ans).toPlainString());
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int L = sc.nextInt();
    sc.close();

    double ans = (double) (L * L * L) / (3d * 3d * 3d);
    System.out.println(BigDecimal.valueOf(ans).toPlainString());
  }
} Main
import java.math.*;
import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int L = sc.nextInt();
    sc.close();

    double ans = (double) (L * L * L) / (3d * 3d * 3d);
    System.out.println(BigDecimal.valueOf(ans).toPlainString());
  }
}
