p02553 AtCoder Beginner Contest 178 - Product Max
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.

Examples

Input

1 2 1 1


Output

2


Input

3 5 -4 -2


Output

-6


Input

-1000000000 0 -1000000000 0


Output

1000000000000000000
```python
lines = map(int,input().split())
a,b,c,d = lines

print(max(a*c,a*d,b*c,b*d))
```