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)


import java.util.Scanner;
import java.math.BigInteger;


class Main{
	public static void main(String args[]){
		
		Scanner input = new Scanner(System.in);

		int a,b,c,d;
		a = b = c = d = 0;

		if(input.hasNextInt())a = input.nextInt();
		if(input.hasNextInt())b = input.nextInt();	
		if(input.hasNextInt())c = input.nextInt();
		if(input.hasNextInt())d = input.nextInt();


		BigInteger A = BigInteger.valueOf(a);
		BigInteger B = BigInteger.valueOf(b);
		BigInteger max1 = A.multiply(BigInteger.valueOf(c));
		BigInteger max2 = A.multiply(BigInteger.valueOf(d));
		BigInteger max3 = B.multiply(BigInteger.valueOf(c));
		BigInteger max4 = A.multiply(BigInteger.valueOf(d));

		int ca = max1.compareTo(max2);
		int cb = max3.compareTo(max4);

		BigInteger f1,f2;
		if(ca>0)f1 = max1;
		else f1 = max2;
		if(cb>0)f2 = max3;
		else f2 = max4;

		int cf = f1.compareTo(f2);
		if(cf>0)System.out.println(f1);
		else System.out.println(f2);


		
	}
}