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: Accepted)

using System;
using System.Linq;
using System.Security.Cryptography.X509Certificates;

namespace AtcoderProblem
{
    class Program
    {
        static void Main(string[] args)
        {
            var line = System.Console.ReadLine();
            var stArrayData = line.Split(' ');
            long a = long.Parse(stArrayData[0]);
            var b = long.Parse(stArrayData[1]);
            var c = long.Parse(stArrayData[2]);
            var d = long.Parse(stArrayData[3]);

            long n = a * c;
            long m = a * d;
            long o = b * c;
            long p = b * d;

            long[] q = { n, m, o, p };
            long r = (q.Max());
            Console.WriteLine(r);
        }         
    }
}