import java.math.BigDecimal;
import java.util.*;
import static java.lang.System.out;

public class Main {
    public static void main(String... args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        BigDecimal decimalL = new BigDecimal(l);
        BigDecimal height = decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal ans = height.multiply(height).multiply(height);
        System.out.println(ans);
    }

} import java.math.BigDecimal; BigDecimal java.math import java.util.*; util.* java import static java.lang.System.out; import static java.lang.System.out; import static java.lang.System.out; public class Main {
    public static void main(String... args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        BigDecimal decimalL = new BigDecimal(l);
        BigDecimal height = decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal ans = height.multiply(height).multiply(height);
        System.out.println(ans);
    }

} Main public static void main(String... args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        BigDecimal decimalL = new BigDecimal(l);
        BigDecimal height = decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal ans = height.multiply(height).multiply(height);
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        BigDecimal decimalL = new BigDecimal(l);
        BigDecimal height = decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal ans = height.multiply(height).multiply(height);
        System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int l = sc.nextInt(); l sc.nextInt() sc.nextInt sc BigDecimal decimalL = new BigDecimal(l); decimalL new BigDecimal(l) BigDecimal height = decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN); height decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN) decimalL.divide decimalL new BigDecimal(3) 7 BigDecimal.ROUND_HALF_DOWN BigDecimal BigDecimal.ROUND_HALF_DOWN BigDecimal ans = height.multiply(height).multiply(height); ans height.multiply(height).multiply(height) height.multiply(height).multiply height.multiply(height) height.multiply height height height System.out.println(ans) System.out.println System.out System System.out ans String... args args public class Main {
    public static void main(String... args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        BigDecimal decimalL = new BigDecimal(l);
        BigDecimal height = decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal ans = height.multiply(height).multiply(height);
        System.out.println(ans);
    }

} public class Main {
    public static void main(String... args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        BigDecimal decimalL = new BigDecimal(l);
        BigDecimal height = decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal ans = height.multiply(height).multiply(height);
        System.out.println(ans);
    }

} Main
import java.math.BigDecimal;
import java.util.*;
import static java.lang.System.out;

public class Main {
    public static void main(String... args) {
        Scanner sc = new Scanner(System.in);
        int l = sc.nextInt();
        BigDecimal decimalL = new BigDecimal(l);
        BigDecimal height = decimalL.divide(new BigDecimal(3),7, BigDecimal.ROUND_HALF_DOWN);
        BigDecimal ans = height.multiply(height).multiply(height);
        System.out.println(ans);
    }

}
