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 Python (3.8.2) (judge verdict: Accepted)

a, b, c, d = map(int, input().split())
ans = 0
if 0 <= a and 0 <= c:
    ans = b*d
elif 0 <= a and d <= 0:
    ans = a*d
elif b <= 0 and 0 <= c:
    ans = b*c
elif b <= 0 and d <= 0:
    ans = a*c
elif a <= 0 <= b and 0 <= c:
    ans = b*d
elif a <= 0 <= b and d <= 0:
    ans = a*c
elif 0 <= a and c <= 0 <= d:
    ans = b*d
elif b <= 0 and c <= 0 <= d:
    ans = a*c
else:
    ans = max(a*c, b*d)

print(ans)