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: Accepted)

#include<stdio.h>
int main()
{
    long long int a,b,c,d;
    long long int A,B,C,D;
    scanf("%lld %lld",&a,&b);
    scanf("%lld %lld",&c,&d);

    A=a*c;
    B=b*c;
    C=a*d;
    D=b*d;
    long long int temp = A;
    if(A>B)
    {
        temp = A;
        A=B;
        B=temp;
    }
    if(B>C)
    {

        temp=B;
        B=C;
        C=temp;
    }
    if(C>D)
    {

        temp=C;
        C=D;
        D=temp;
    }
    if(D>A)
    {
        temp=D;
        D=A;
        A=temp;
    }
    if(A>B)
    {

        temp=A;
        A=B;
        B=temp;
    }
    printf("%lld\n",temp);
    return 0;

}