Problem:
Score : 200 points

Problem Statement

Given are integers a,b,c and d.
If x and y are integers and a \leq x \leq b and c\leq y \leq d hold, what is the maximum possible value of x \times y?

Constraints

-10^9 \leq a \leq b \leq 10^9

-10^9 \leq c \leq d \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

a b c d

Output

Print the answer.

Sample Input 1

1 2 1 1

Sample Output 1

2

If x = 1 and y = 1 then x \times y = 1.
If x = 2 and y = 1 then x \times y = 2.
Therefore, the answer is 2.

Sample Input 2

3 5 -4 -2

Sample Output 2

-6

The answer can be negative.

Sample Input 3

-1000000000 0 -1000000000 0

Sample Output 3

1000000000000000000

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

fun main(args: Array<String>) {
    val (a, b, c, d) = readLine()!!.split(' ').map { it.toLong() }

    val min1 = Math.min(a, b)
    val max1 = Math.max(a, b)

    val min2 = Math.min(c, d)
    val max2 = Math.max(c, d)

    when {
        // + +
        max1 > 0 && max2 > 0 -> {
            println(max1 * max2)
        }
        // + -
        max1 > 0 && max2 <= 0 -> {
            println(Math.max(min1 * max2, max1 * min2))
        }

        // - +
        max1 <= 0 && max2 > 0 -> {
            println(Math.max(max1 * min2, max2 * min1))
        }
        // - -
        max1 <= 0 && max2 <= 0 -> {
            println(min1 * min2)
        }
        else -> {
            println(0)
        }
    }
}