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.Linq;

   class Program
    {
        static void Main()
        {
            var args = Console.ReadLine().Split().ToList().ConvertAll(x=>double.Parse(x));
            var a = args[0];
            var b = args[1];
            var c = args[2];
            var d = args[3];
            var ans = (double)0;
            ans = a * c;
            if (a * d > ans) ans = a * d;
            if (b * c > ans) ans = b * c;
            if (b * d > ans) ans = b * d;
            Console.WriteLine(ans);
        }
    }