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 C++ (GCC 9.2.1) (judge verdict: Accepted)

#include<iostream>
using namespace std;
int main()
{
	long long a,b,c,d,x1,x2,y1,y2;
  	cin>>a>>b>>c>>d;
  	x1=a*c;
  	x2=a*d;
  	y1=b*c;
  	y2=b*d;
  	if(x1>x2 && x1>y1 && x1>y2)
    {
		cout<<x1;
    }
  	else if(x2>x1 && x2>y1 && x2>y2)
      cout<<x2;
  	else if(y1>x1 && y1>x2 && y1>y2 )
      cout<<y1;
  else
    cout<<y2;
   
}