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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <vector>
#include <string>
#include <cstring>
using namespace std;

int main(){
	int a, b, c, d, ans, ab, bc, cd, ad, bd,ac;
	cin >> a >> b >> c >> d;
	bc = b * c;
	ac = a * c;
	ad = a * d;
	bd = b * d;
	ans = bc;
	if (ac > ans) {
		ans = ac;
	}
	if (ad > ans) {
		ans = ad;
	}
	if (bd > ans) {
		ans = bd;
	}
	cout << ans;
	return 0;

}