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;
import java.math.BigDecimal;
class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double a[] = new double[2];
        double c[] = new double[2];
        a[0] = sc.nextDouble();
        a[1] = sc.nextDouble();
        c[0] = sc.nextDouble();
        c[1] = sc.nextDouble();

        double max =  Double.NEGATIVE_INFINITY;
        for(int i=0;i<a.length;i++){
            double x = a[i];
            for(int j=0;j<c.length;j++){
                double y = c[j];
              //System.out.println(x*y);
                if(x*y>max) max = x*y;
            }
        }
        System.out.print(max);
    }
}