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: Accepted)

#include <bits/stdc++.h>
using namespace std ;
using V_2 = vector<vector<int>> ;
using Gragh = vector<vector<char>> ;
using P = pair<int,int> ;
using ll = long long ;

int main(){
  ll a , b , c , d ;
  ll ans[4] ;
  cin >> a >> b >> c >> d ;
  ans[0] = a * c ;
  ans[1] = a * d ;
  ans[2] = b * c ;
  ans[3] = b * d ;
  sort(ans,ans+4) ;
  cout << ans[3] << endl ;
}