Given is a positive integer L. Find the maximum possible volume of a rectangular cuboid whose sum of the dimensions (not necessarily integers) is L.
def maxvolume (s): 

    maxvalue = 0

  

    # for length 

    i = 1

    for i in range(s - 1): 

        j = 1

          

        # for breadth 

        for j in range(s): 

              

            

            k = s - i - j 

              

            

            maxvalue = max(maxvalue, i * j * k) 

              

    return maxvalue 
n = int(input())
x = n/3
y = pow(x,3)
print("{0:.12f}".format(y))