Problem:
Score : 300 points

Problem Statement

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.

Constraints

1 ≤ L ≤ 1000

L is an integer.

Input

Input is given from Standard Input in the following format:

L

Output

Print the maximum possible volume of a rectangular cuboid whose sum of the dimensions (not necessarily integers) is L.
Your output is considered correct if its absolute or relative error from our answer is at most 10^{-6}.

Sample Input 1

3

Sample Output 1

1.000000000000

For example, a rectangular cuboid whose dimensions are 0.8, 1, and 1.2 has a volume of 0.96.

On the other hand, if the dimensions are 1, 1, and 1, the volume of the rectangular cuboid is 1, which is greater.

Sample Input 2

999

Sample Output 2

36926037.000000000000

Solution in Kotlin (1.3.71) (judge verdict: Wrong Answer)

fun main() {
    println(res(nextLong()))
}

fun res(n: Long): String {
    return if (n == 1L) {
        0.036926037.toString()
    } else if (n == 2L) {
        0.295408296.toString()
    } else {
        val i = n * 1000 / 3
        val resStr = (i * i * i).toString()
        resStr.substring(0, resStr.length - 9) + "." + resStr.substring(resStr.length - 9, resStr.length)
    }
}

fun next() = readLine()!!
fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextDouble() = next().toDouble()
fun nextList() = next().split(' ')
fun nextIntList() = nextList().map { it.toInt() }
fun nextLongList() = nextList().map { it.toLong() }
fun nextDoubleList() = nextList().map { it.toDouble() }