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: Accepted)

"use strict"

function Main(input) {
  let lines = input.split('\n');
  const [a, b, c, d] = lines[0].split(' ').map(BigInt);

  let product_matrix = [];
  product_matrix.push(a * c);
  product_matrix.push(a * d);
  product_matrix.push(b * c);
  product_matrix.push(b * d);
  const max = product_matrix.reduce((a,b)=>a>b?a:b)

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

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