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<stdio.h>
main()
{
    int a, b, c, d, max;
    scanf("%d%d%d%d", &a, &b, &c, &d);
    int s[3];
    s[0]=a*c;
    s[1]=a*d;
    s[2]=b*c;
    s[3]=b*d;

    max = s[0];
    for(int i=0; i<4; i++)
    {
        if(max>s[i+1]) max=s[i];
        else max=s[i+1];
    }
    printf("%d", max);
}