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<stdio.h>
int main()
{
    long long int a,b,c,d;
    long long int max,s1,s2,s3,s4;
    scanf("%lld%lld%lld%lld",&a,&b,&c,&d);
    s1=a*c;
    s2=a*d;
    s3=b*c;
    s4=b*d;
    if(s1>=s2&&s1>=s3&&s1>=s4){printf("%lld\n",s1);}
    else if(s2>=s1&&s2>=s3&&s2>=s4){printf("%lld\n",s2);}
    else if(s3>=s2&&s3>=s1&&s3>=s4){printf("%lld\n",s3);}
    else if(s4>=s2&&s4>=s3&&s4>=s1){printf("%lld\n",s4);}
    return 0;

}