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 1.8.0) (judge verdict: Wrong Answer)

import java.util.Scanner;

public class Main {
  
  public static void main(String[] args) {
    int num[] = new int[4]; 
    Scanner scanner = new Scanner(System.in);
    for (int i = 0; i < 4; i++){
        num[i] = Integer.parseInt(scanner.next());
    }
    scanner.close();
    long max = -1000000000;
    long tmp = 0;

    for (int j = 0; j < 2; j++){
      for (int k = 2; k < 4; k++){
        tmp = (long)num[j] * (long)num[k];
        if (max < tmp){
          max = tmp;
        }
      }
    }
    System.out.println(max);
  }
}