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)

//Created by Amaxul on 9/13/2020.

import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

import static java.lang.Math.max;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner in = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        long a = in.nextInt(), b = in.nextInt();
        long c = in.nextInt(), d = in.nextInt();

        long max = getMin(a, b, c, d);
        pw.println(max);

        pw.close();
    }

    static long getMin(long a, long b, long c, long d) {
        long max = a * c;
        max = max(max, a * d);
        max = max(max, b * c);
        max = max(max, b * d);
        if ((a <= 0 && b >= 0) || (c <= 0 && d >= 0)) {
            max = max(max, 0);
        }
        return max;
    }

    static void debug(Object... obj) {
        System.err.println(Arrays.deepToString(obj));
    }
}