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 <bits/stdc++.h>
using namespace std;
#define ll long long
#define IOS ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define MOD2 1000000007
#define MOD 1000000009
#define endl "\n"
#define pii pair <int, int>
#define pll pair <ll, ll>
#define vvi vector <vector<int>>
#define F first
#define S second




int main()
{   
    IOS;
        #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
        #endif
    
    ll a, b, c, d;
    cin >> a >> b >> c >> d;
    cout << max((ll)a * c, (ll)b * d);
        

    
    
return 0;
}