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.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    long b = sc.nextLong();
    long c = sc.nextLong();
    long d = sc.nextLong();
    long x = 0;
    long y = 0;
    if(a < 0 && b < 0 && c > 0 && d > 0){
      if(a < b){
        x = b;
      }
      else{
        x = a;
      }
      if(c < d){
        y = c;
      }
      else{
        y = d;
      }
    }
    else if(a > 0 && b > 0 && c < 0 && d < 0){
      if(a < b){
        x = a;
      }
      else{
        x = b;
      }
      if(c < d){
        y = d;
      }
      else{
        y = c;
      }
    }
    else if(a <= 0 && b <= 0 && c <= 0 && d <= 0){
      if(a < b){
        x = a;
      }
      else{
        x = b;
      }
      if(c < d){
        y = c;
      }
      else{
        y = d;
      }
    }
    else if(a > 0 && b > 0 && c > 0 && d > 0){
      if(a < b){
        x = b;
      }
      else{
        x = a;
      }
      if(c < d){
        y = d;
      }
      else{
        y = c;
      }
    }
  }
}