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.ComponentModel;

namespace Constest
{
    class Program
    {
        static void Main(string[] args)
        {
            string line = Console.ReadLine();
            string[] stArrayData = line.Split(' ');
            stArrayData = line.Split(' ');
            long a = long.Parse(stArrayData[0]);
            long b = long.Parse(stArrayData[1]);
            long c = long.Parse(stArrayData[2]);
            long d = long.Parse(stArrayData[3]);
            long ans = 0;
            
            if(((b < 0) && (d < 0)) || ((0 <= b) && (0 <= d)))
            {
                if((a < 0) && (c < 0))
                {
                    ans = ((b * d) <= (a * c)) ? (a * c) : (b * d);
                }
                else
                {
                    ans = b * d;
                }
            }else if ((((0 <= a) && (0 <= c)) && ((b < 0) && (d < 0))) || (((0 <= b) && (0 <= d)) && ((a < 0) && (c < 0))))
            {
                ans = a * c;
            }else if(0 <= b)
            {
                ans = a * d;
            }
            else
            {
                ans = b * c;
            }

                Console.WriteLine(ans);
        }
    }
}