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;

namespace Product_Max
{
    class Program
    {
        static void Main(string[] args)
        {
            int a, b, c, d;
            long x, y;

            string inD0 = Console.ReadLine();
            string[] cngD0 = inD0.Split(' ');

            a= int.Parse(cngD0[0]);
            b= int.Parse(cngD0[1]);
            c= int.Parse(cngD0[2]);
            d=int.Parse(cngD0[3]);

            if(b <0 && d > 0)
            {
                x = b;
                y = c;

            }
            else
            {
                if  (b > 0 && d < 0)
                {
                    x = a;
                    y = d;

                }
                else
                {
                    if (b == 0 && d == 0)
                    {
                        x = a;
                        y = c;
                    }
                    else
                    {
                        x = b;
                        y = d;

                    }


                }

            }

            Console.WriteLine(x*y);
        }
    }
}