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

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextDouble();
        sc.close();
        double a = L / 3;
        double b = a;
        double c = b;
        double remain = L - (a + b + c);
        a += remain;
        double res = a * b * c;
        System.out.println(BigDecimal.valueOf(res).toPlainString());
    }

} import java.math.BigDecimal; BigDecimal java.math import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextDouble();
        sc.close();
        double a = L / 3;
        double b = a;
        double c = b;
        double remain = L - (a + b + c);
        a += remain;
        double res = a * b * c;
        System.out.println(BigDecimal.valueOf(res).toPlainString());
    }

} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextDouble();
        sc.close();
        double a = L / 3;
        double b = a;
        double c = b;
        double remain = L - (a + b + c);
        a += remain;
        double res = a * b * c;
        System.out.println(BigDecimal.valueOf(res).toPlainString());
    } main {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextDouble();
        sc.close();
        double a = L / 3;
        double b = a;
        double c = b;
        double remain = L - (a + b + c);
        a += remain;
        double res = a * b * c;
        System.out.println(BigDecimal.valueOf(res).toPlainString());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double L = sc.nextDouble(); L sc.nextDouble() sc.nextDouble sc sc.close() sc.close sc double a = L / 3; a L / 3 L 3 double b = a; b a double c = b; c b double remain = L - (a + b + c); remain L - (a + b + c) L (a + b + c) a + b + c a b c a += remain a remain double res = a * b * c; res a * b * c a * b * c a b c System.out.println(BigDecimal.valueOf(res).toPlainString()) System.out.println System.out System System.out BigDecimal.valueOf(res).toPlainString() BigDecimal.valueOf(res).toPlainString BigDecimal.valueOf(res) BigDecimal.valueOf BigDecimal res String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextDouble();
        sc.close();
        double a = L / 3;
        double b = a;
        double c = b;
        double remain = L - (a + b + c);
        a += remain;
        double res = a * b * c;
        System.out.println(BigDecimal.valueOf(res).toPlainString());
    }

} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextDouble();
        sc.close();
        double a = L / 3;
        double b = a;
        double c = b;
        double remain = L - (a + b + c);
        a += remain;
        double res = a * b * c;
        System.out.println(BigDecimal.valueOf(res).toPlainString());
    }

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

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextDouble();
        sc.close();
        double a = L / 3;
        double b = a;
        double c = b;
        double remain = L - (a + b + c);
        a += remain;
        double res = a * b * c;
        System.out.println(BigDecimal.valueOf(res).toPlainString());
    }

}
