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 {
    void run(String[] args){
        Scanner scan=new Scanner(System.in);
        long a=scan.nextLong();
        long b=scan.nextLong();
        long c=scan.nextLong();
        long d=scan.nextLong();
        long max=Long.MIN_VALUE;
        long answer;
        answer=a*c;
        if(max<answer){
            max=answer;
        }
        answer=a*d;
        if(max<answer){
            max=answer;
        }
        answer=b*c;
        if(max<answer){
            max=answer;
        }
        answer=b*d;
        if(max<answer){
            max=answer;
        }
        System.out.println(max);
    }
    public static void main(String args[]){
        Main printer = new Main();
        printer.run(args);
    }
}