Score : 200 points
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?
Input is given from Standard Input in the following format:
a b c d
Print the answer.
1 2 1 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.
3 5 -4 -2
-6
The answer can be negative.
-1000000000 0 -1000000000 0
1000000000000000000