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;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace B___Product_Max
{
    class Program
    {
        static void Main(string[] args)
        {
            const bool debug = false;

            while (debug)
            {
                var input = Console.ReadLine().Split(' ');
                long a = long.Parse(input[0]);
                long b = long.Parse(input[1]);
                long c = long.Parse(input[2]);
                long d = long.Parse(input[3]);


                var result = Math.Max(Math.Max(a * c, a * d), Math.Max(b * c, b * d));




                Console.WriteLine(result);


            }
        }
    }
}