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;

class main{
  public static void Main(string[] args){
    string[] s = Console.ReadLine().Split(" ");
    long a = long.Parse(s[0]);
    long b = long.Parse(s[1]);
    long c = long.Parse(s[2]);
    long d = long.Parse(s[3]);
    
    long max = 0;
    long num1 = a*c;
    long num2 = a*d;
    max = Math.Max(num1, num2);
    
    long num3 = b*c;
    max = Math.Max(max, num3);
    
    long num4 = b*d;
    max = Math.Max(max, num4);
    Console.WriteLine(max);
  }
}