import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scanner = new Scanner(System.in);
		int l = scanner.nextInt();
//		double result = 0;
//		for(int i = 1; i <= l-2; i++){
//			for(int j = l-i-1; j >= 1; j--){
//				int k = l - i - j;
//				result = Math.max(result, i*j*k);
////				System.out.println(i+","+j+","+k+" : " + result);
//			}
//		}
		double rrr = 0d;
		double a = 0.1d;
		while(a <= l - 0.2d){
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		}
		float ll = l;

		System.out.println(ll/3*(ll/3)*(ll/3));
	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scanner = new Scanner(System.in);
		int l = scanner.nextInt();
//		double result = 0;
//		for(int i = 1; i <= l-2; i++){
//			for(int j = l-i-1; j >= 1; j--){
//				int k = l - i - j;
//				result = Math.max(result, i*j*k);
////				System.out.println(i+","+j+","+k+" : " + result);
//			}
//		}
		double rrr = 0d;
		double a = 0.1d;
		while(a <= l - 0.2d){
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		}
		float ll = l;

		System.out.println(ll/3*(ll/3)*(ll/3));
	}

} Main public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scanner = new Scanner(System.in);
		int l = scanner.nextInt();
//		double result = 0;
//		for(int i = 1; i <= l-2; i++){
//			for(int j = l-i-1; j >= 1; j--){
//				int k = l - i - j;
//				result = Math.max(result, i*j*k);
////				System.out.println(i+","+j+","+k+" : " + result);
//			}
//		}
		double rrr = 0d;
		double a = 0.1d;
		while(a <= l - 0.2d){
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		}
		float ll = l;

		System.out.println(ll/3*(ll/3)*(ll/3));
	} main {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scanner = new Scanner(System.in);
		int l = scanner.nextInt();
//		double result = 0;
//		for(int i = 1; i <= l-2; i++){
//			for(int j = l-i-1; j >= 1; j--){
//				int k = l - i - j;
//				result = Math.max(result, i*j*k);
////				System.out.println(i+","+j+","+k+" : " + result);
//			}
//		}
		double rrr = 0d;
		double a = 0.1d;
		while(a <= l - 0.2d){
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		}
		float ll = l;

		System.out.println(ll/3*(ll/3)*(ll/3));
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int l = scanner.nextInt(); l scanner.nextInt() scanner.nextInt scanner double rrr = 0d; rrr 0d double a = 0.1d; a 0.1d while(a <= l - 0.2d){
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		} a <= l - 0.2d a l - 0.2d l 0.2d {
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		} double b = l - a; b l - a l a while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			} b > 0 b 0 {
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			} double c = l - a - b; c l - a - b l - a - b l a b rrr = Math.max(rrr, a * b * c) rrr Math.max(rrr, a * b * c) Math.max Math rrr a * b * c a * b * c a b c b -= 0.1d b 0.1d a += 0.1d a 0.1d float ll = l; ll l System.out.println(ll/3*(ll/3)*(ll/3)) System.out.println System.out System System.out ll/3*(ll/3)*(ll/3) ll/3*(ll/3)*(ll/3) ll/3 ll 3 (ll/3) ll 3 (ll/3) ll 3 String[] args args public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scanner = new Scanner(System.in);
		int l = scanner.nextInt();
//		double result = 0;
//		for(int i = 1; i <= l-2; i++){
//			for(int j = l-i-1; j >= 1; j--){
//				int k = l - i - j;
//				result = Math.max(result, i*j*k);
////				System.out.println(i+","+j+","+k+" : " + result);
//			}
//		}
		double rrr = 0d;
		double a = 0.1d;
		while(a <= l - 0.2d){
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		}
		float ll = l;

		System.out.println(ll/3*(ll/3)*(ll/3));
	}

} public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scanner = new Scanner(System.in);
		int l = scanner.nextInt();
//		double result = 0;
//		for(int i = 1; i <= l-2; i++){
//			for(int j = l-i-1; j >= 1; j--){
//				int k = l - i - j;
//				result = Math.max(result, i*j*k);
////				System.out.println(i+","+j+","+k+" : " + result);
//			}
//		}
		double rrr = 0d;
		double a = 0.1d;
		while(a <= l - 0.2d){
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		}
		float ll = l;

		System.out.println(ll/3*(ll/3)*(ll/3));
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scanner = new Scanner(System.in);
		int l = scanner.nextInt();
//		double result = 0;
//		for(int i = 1; i <= l-2; i++){
//			for(int j = l-i-1; j >= 1; j--){
//				int k = l - i - j;
//				result = Math.max(result, i*j*k);
////				System.out.println(i+","+j+","+k+" : " + result);
//			}
//		}
		double rrr = 0d;
		double a = 0.1d;
		while(a <= l - 0.2d){
			double b = l - a;
			while(b > 0){
				double c = l - a - b;
				rrr = Math.max(rrr, a * b * c);
				b -= 0.1d;
			}
			a += 0.1d;
		}
		float ll = l;

		System.out.println(ll/3*(ll/3)*(ll/3));
	}

}
