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 JavaScript (Node.js 12.16.1) (judge verdict: Wrong Answer)

function Main(input) {

	// 1行目がinput[0], 2行目がinput[1], …に入る
	input = input.split("\n");
    
    let [a,b,c,d] = input[0].split(" ").map(BigInt);
    
    let ac = a * c;
    let ad = a * d;
    let bc = b * c;
    let bd = b * d;
    
    let max = [ac,ad,bc,bd].sort()[3];
    
    if (max < 0) {
        if ((a < 0 && b > 0) || (a > 0 && b < 0)) max = 0;
        if ((c < 0 && d > 0) || (c > 0 && d < 0)) max = 0;
    }
    
    console.log(max.toString());
    
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));