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)

//package atcoder.beginner_178;

import java.io.*;
import java.util.StringTokenizer;

public class Main {

    public static void main (String[] args) throws Exception {

        String s = "1 2 1 1";

//        br = new BufferedReader(new StringReader(s));
        br = new BufferedReader(new InputStreamReader(System.in));
        bw = new BufferedWriter(new OutputStreamWriter(System.out));

        rl(); long a = nlo(), b=nlo(), c=nlo(), d=nlo();
        if (a<=0 && b<=0 && c>=0 && d>=0) {
            bw.write( (b*c) + "\n");
        } else {
            bw.write( Math.max(a*c, b*d) + "\n");
        }
        bw.flush();
    }

    static BufferedReader br; static BufferedWriter bw; static StringTokenizer st;
    static void rl() throws Exception{ st = new StringTokenizer(br.readLine()); }
    static long nlo(){ return Long.parseLong(st.nextToken()); }
    static int nin(){ return Integer.parseInt(st.nextToken()); }
    /*private static void te(){}*/
    static double ndo(){ return Double.parseDouble(st.nextToken()); }
    static char[] nca(){ return st.nextToken().toCharArray(); }
}