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 C# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
class Program
{

    static void Main()
    {
        string[] ABCD = Console.ReadLine().Split(' ');
        long A = long.Parse(ABCD[0]);
        long B = long.Parse(ABCD[1]);
        long C = long.Parse(ABCD[2]);
        long D = long.Parse(ABCD[3]);
        long E = 0;

        if (B <= 0 && D <= 0)
        {
            E = A * C;
        }
        else if (B >= 0 && D <= 0)
        {
            E = A * D;
        }
        else if (B <= 0 && D >= 0)
        {
            E = B * C;
        }
        else
        {
            E = B * D;
        }

        Console.WriteLine(E);
    }

}