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++ (Clang 10.0.0) (judge verdict: Wrong Answer)

#include<iostream>
typedef long long ll;

using namespace std;

int main()
{
    ll a,b,c,d;
    cin>>a>>b>>c>>d;
    if(a>=0&&b>=0&&c>=0&&d>=0)
    {
        cout<<max(a,b)*max(c,d)<<endl;
    }
    else if(a<=0&&b>=0&&c>=0&&d>=0)
    {
        cout<<b*max(c,d)<<endl;
    }
    else if(a>=0&&b<=0&&c>=0&&d>=0)
    {
        cout<<a*max(c,d)<<endl;
    }
    else if(a<=0&&b<=0&&c>=0&&d>=0)
    {
        cout<<max(a,b)*min(c,d)<<endl;
    }
    else if(a>=0&&b>=0&&c<=0&&d>=0)
    {
        cout<<max(a,b)*d<<endl;
    }
    else if(a>=0&&b>=0&&c<=0&&d<=0)
    {
        cout<<min(a,b)*max(c,d)<<endl;
    }
    else if(a<=0&&b<=0&&c<=0&&d<=0)
    {
        cout<<min(a,b)*min(c,d)<<endl;
    }

}