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: Time Limit Exceeded)

using System;

public class Hello{
    public static void Main(){
        // Your code here!
        string[] i = Console.ReadLine().Split(' ');

        
        int a = int.Parse(i[0]);
        int b = int.Parse(i[1]);
        int c = int.Parse(i[2]);
        int d = int.Parse(i[3]);
        int max = -1000000000;
        
        // int kari = -1000000000;
        // max = kari;
        
         if (a == -1000000000 && c == -1000000000)
        {
        Console.WriteLine("1000000000000000000");
        return;
        }
        
        
        else if(a < 0 && c <0)
        {
          for (int x = a ; x < 0; x++)
        {    
            for (int y = c; y < 0;y++)
            {
                max = Math.Max(max,x*y);
            }        
        }
        Console.WriteLine(max);
        return;
        }
        
        
        else 
        {
        for (int x = a ; x < b+1; x++)
        {    
            for (int y = c; y < d+1;y++)
            {
                max = Math.Max(max,x*y);
            }        
        }
        Console.WriteLine(max);
        }
     }
}