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>
#include<stdlib.h>
 
int main()
{
  long long int a,b,c,d;
  scanf("%lld %lld %lld %lld",&a,&b,&c,&d);
  
 	//printf("%lld %lld %lld %lld\n",a,b,c,d);
 
  	//printf("%lld",100000000*100000000l);
  
  
    
  if (a<=0 && 0<=b && c<=0 && 0<=d )
  {
    if ( (b*d) >= (a*c) )
    {
    printf("%lld",b*d);
    return 0;
    } else {
    printf("%lld",a*c);
    return 0;  
    }
  }
  
    if (0<=a && d<=0 && c<=0 && d<=0)
  {
    printf("%lld",a*d);
    return 0;
  }
  
   if (a<=0 && b<=0 && 0<=c && 0<=d )
  {
    printf("%lld",b*c);
    return 0;
  }
   
  if (0<=b && 0<=d )
  {
    printf("%lld",b*d);
    return 0;
  }

   
  if (a<=0 && c<=0)
  {
   	printf("%lld",a*c);
   	return 0;
  }
  
  
  return 0;
}