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.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        long x;
        long y;
        long s;
        long t;
        long z;
        long zz;
        long zzz;
        
        if(b<0 && d<0 ) {
        	z=a*c;
        } else if(a>0 && c>0) {
        	z=b*d;
        }else if(b<0 && c>0) {
        	z=b*c;
        }else if(a>0 && d<0) {
        	z=a*d;
        } else {
        	s=a*c;
        	t=b*d;
        	x=a*d;
        	y=b*c;
        	zz=Math.max(s,t);
        	zzz=Math.max(zz,x);
        	z=Math.max(zzz,y);
        }
        
        System.out.println(z);
        

    }
}