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# (Mono-csc 3.5.0) (judge verdict: Accepted)


using System;
using System.Linq;

namespace ConsoleApp1
{
	class Program
	{
		static void Main(string[] args)
		{
			var inputs = Console.ReadLine().Split(' ');
			var a = long.Parse(inputs[0]);
			var b = long.Parse(inputs[1]);
			var c = long.Parse(inputs[2]);
			var d = long.Parse(inputs[3]);

			var s = new[]
			{
				a * c,
				a * d,
				b * c,
				b * d
			};

			Console.WriteLine(s.Max());
		}
	}
}