import java.util.*;
import java.math.*;
public class Main {
    public static void main(String[] args){
      // 入力
      Scanner sc = new Scanner(System.in);
      int L = sc.nextInt();
      
      // 体積最大値算出
      BigDecimal bdL = BigDecimal.valueOf(L);
      BigDecimal three = BigDecimal.valueOf(3);
      BigDecimal ave = bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP);
      BigDecimal max = ave;
      max = max.multiply(ave);
      max = max.multiply(ave);
      
      // 出力
      System.out.println(max);
    }
    
} import java.util.*; util.* java import java.math.*; math.* java public class Main {
    public static void main(String[] args){
      // 入力
      Scanner sc = new Scanner(System.in);
      int L = sc.nextInt();
      
      // 体積最大値算出
      BigDecimal bdL = BigDecimal.valueOf(L);
      BigDecimal three = BigDecimal.valueOf(3);
      BigDecimal ave = bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP);
      BigDecimal max = ave;
      max = max.multiply(ave);
      max = max.multiply(ave);
      
      // 出力
      System.out.println(max);
    }
    
} Main public static void main(String[] args){
      // 入力
      Scanner sc = new Scanner(System.in);
      int L = sc.nextInt();
      
      // 体積最大値算出
      BigDecimal bdL = BigDecimal.valueOf(L);
      BigDecimal three = BigDecimal.valueOf(3);
      BigDecimal ave = bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP);
      BigDecimal max = ave;
      max = max.multiply(ave);
      max = max.multiply(ave);
      
      // 出力
      System.out.println(max);
    } main {
      // 入力
      Scanner sc = new Scanner(System.in);
      int L = sc.nextInt();
      
      // 体積最大値算出
      BigDecimal bdL = BigDecimal.valueOf(L);
      BigDecimal three = BigDecimal.valueOf(3);
      BigDecimal ave = bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP);
      BigDecimal max = ave;
      max = max.multiply(ave);
      max = max.multiply(ave);
      
      // 出力
      System.out.println(max);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int L = sc.nextInt(); L sc.nextInt() sc.nextInt sc BigDecimal bdL = BigDecimal.valueOf(L); bdL BigDecimal.valueOf(L) BigDecimal.valueOf BigDecimal L BigDecimal three = BigDecimal.valueOf(3); three BigDecimal.valueOf(3) BigDecimal.valueOf BigDecimal 3 BigDecimal ave = bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP); ave bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP) bdL.divide bdL three 6 BigDecimal.ROUND_HALF_UP BigDecimal BigDecimal.ROUND_HALF_UP BigDecimal max = ave; max ave max = max.multiply(ave) max max.multiply(ave) max.multiply max ave max = max.multiply(ave) max max.multiply(ave) max.multiply max ave System.out.println(max) System.out.println System.out System System.out max String[] args args public class Main {
    public static void main(String[] args){
      // 入力
      Scanner sc = new Scanner(System.in);
      int L = sc.nextInt();
      
      // 体積最大値算出
      BigDecimal bdL = BigDecimal.valueOf(L);
      BigDecimal three = BigDecimal.valueOf(3);
      BigDecimal ave = bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP);
      BigDecimal max = ave;
      max = max.multiply(ave);
      max = max.multiply(ave);
      
      // 出力
      System.out.println(max);
    }
    
} public class Main {
    public static void main(String[] args){
      // 入力
      Scanner sc = new Scanner(System.in);
      int L = sc.nextInt();
      
      // 体積最大値算出
      BigDecimal bdL = BigDecimal.valueOf(L);
      BigDecimal three = BigDecimal.valueOf(3);
      BigDecimal ave = bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP);
      BigDecimal max = ave;
      max = max.multiply(ave);
      max = max.multiply(ave);
      
      // 出力
      System.out.println(max);
    }
    
} Main
import java.util.*;
import java.math.*;
public class Main {
    public static void main(String[] args){
      // 入力
      Scanner sc = new Scanner(System.in);
      int L = sc.nextInt();
      
      // 体積最大値算出
      BigDecimal bdL = BigDecimal.valueOf(L);
      BigDecimal three = BigDecimal.valueOf(3);
      BigDecimal ave = bdL.divide(three, 6, BigDecimal.ROUND_HALF_UP);
      BigDecimal max = ave;
      max = max.multiply(ave);
      max = max.multiply(ave);
      
      // 出力
      System.out.println(max);
    }
    
}