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 PyPy3 (7.3.0) (judge verdict: Accepted)

import sys

def solve():
    A, B, C, D = [int(i) for i in input().split()]
    ans = sys.maxsize * -1
    X = [0, A, B] if A <= 0 <= B else [A, B]
    Y = [0, C, D] if A <= 0 <= B else [C, D]
    for x in X:
        for y in Y:
            ans = max(ans, x * y)
    print(ans)

if __name__ == "__main__":
    solve()