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: Runtime Error)

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

namespace ConsoleApplication3
{
	class Program
	{
		static void Main(string[] args)
		{
			var inputIntArray = Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray();
			List<long> intList = new List<long>();
			intList.Add(inputIntArray[0] * inputIntArray[2]);
			intList.Add(inputIntArray[0] * inputIntArray[3]);
			intList.Add(inputIntArray[1] * inputIntArray[2]);
			intList.Add(inputIntArray[1] * inputIntArray[3]);
			long result = intList.Max();
			Console.WriteLine(result);
			Console.ReadKey();

		}
	}
}