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 Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.Scanner;
 
class Main{
 public static void main(String[] args){
   Scanner scanner = new Scanner(System.in);
   double a = scanner.nextDouble();
   double b = scanner.nextDouble();
   double c = scanner.nextDouble();
   double d = scanner.nextDouble();
   
   double[] e= new double[]{a*c,a*d,b*c,b*d};
   
   double num = e[0];
   
   for(int i=1;i<4;i++) if(num < e[i]) num = e[i];
   
   System.out.println(num);
   
 }
   
}