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;
 
public class Main {
	public static void main (String[] args) {
		Scanner in = new Scanner(System.in);
		long a = in.nextLong();
		long b = in.nextLong();
		long c = in.nextLong();
		long d = in.nextLong();
		long prod = Long.MIN_VALUE;
      prod = Math.max(prod, b*d);
      prod = Math.max(prod, a*c);
        prod = Math.max(prod, Math.min(b,d) * Math.max(a,c));
      System.out.println(prod);
	}
}