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: Wrong Answer)

#include <stdio.h>
int main(void) {
int a,b,c,d,e,f,g,h;
scanf("%d%d%d%d%d%d%d%d",&a,&b,&c,&d,&e,&f,&g,&h);
a*c==e;
a*d==f;
b*c==g;
b*d==h;
if(f<=e&&g<=e&&h<=e)
printf("%d",e);
else if(e<=f&&g<=f&&h<=f)
printf("%d",f);
else if(e<=g&&f<=g&&h<=g)
printf("%d",g);
else
printf("%d",h);
return 0;
}