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;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] In = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            long a = In[0];
            long b = In[1];
            long c = In[2];
            long d = In[3];
            long[] A = new long[] { a * c, a * d, b * c, b * d };
            long max = -1001001001001001001;
            foreach(var i in A)
            {
                max = (long)Math.Max(max, i);
            }
            Console.WriteLine(max);
        }
    }
    //class Program
    //{
    //    static void Main(string[] args)
    //    {
    //        int[] In = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
    //        long a = In[0];
    //        long b = In[1];
    //        long c = In[2];
    //        long d = In[3];
    //        if(0<a && 0 <c)
    //        {
    //            Console.WriteLine(b * d);
    //        }
    //        else if(b<=0 && d <= 0)
    //        {
    //            Console.WriteLine(a*c);
    //        }
    //        else
    //        {
    //            Console.WriteLine(-1 * (int)Math.Min(Math.Abs(a), Math.Abs(a)) * (int)Math.Min(Math.Abs(c), Math.Abs(d)));
    //        }
    //    }
    //}
}