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)

process.stdin.resume();
process.stdin.setEncoding('utf-8');
 
let inputString = '';
let currentLine = 0;
 
process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});
 
process.stdin.on('end', _ => {
    inputString = inputString.split(/\n/);
    main();    
});
 
function readLine() {
    return inputString[currentLine++];
}

function main() {
  const [a, b, c, d] = readLine().split(/\s/).map(BigInt)
  console.log([a * c, a * d, b * c, b * d].reduce((a, b) => a > b ? a : b).toString())
}