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) {
  const [a, b, c, d] = input.split(" ").map(x => BigInt(x));
   
  let result = a * c;

  if (a * d) result = a * d;
  if (b * c) result = b * c;
  if (b * d) result = b * d;

  console.log(result.toString());
}

// Main(require("fs").readFileSync("sample.txt", "utf8"));  // テスト用
Main(require("fs").readFileSync("/dev/stdin", "utf8"));   // 提出用