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: Accepted)

import java.util.Scanner;
import java.util.Vector;

class Main {
    public static void main(String[] args) {
        Scanner ler = new Scanner(System.in);
        long a = ler.nextLong(), b = ler.nextLong(), c = ler.nextLong(), d = ler.nextLong();
        Vector<Long> v = new Vector<>();

        v.add(a*c);
        v.add(a*d);
        v.add(b*c);
        v.add(b*d);
        v.sort(null);

        System.out.println(v.lastElement());
    }   
}