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>
#define ll long long
#define num_lim 10000
#define MAXN 100000
#define BIGN 1000000000
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define all(v) v.begin(),v.end()
#define sortarr(arr_name,size) sort(arr_name,arr_name + size)
#define test int t;cin >> t;while(t--)
#define take(data_type,variable_name) data_type variable_name;cin >> variable_name;
#define forn(variable_name,start,end,step) for(int variable_name = start;variable_name<end;variable_name+=step)
#define in_arr(data_type,arr,n) data_type arr[n];forn(i,0,n,1) cin >> arr[i]
using namespace std;

int main(){
    ll int a,b,c,d;
    cin >> a >> b >> c >> d;
    cout << max(a*b,c*d) << '\n';
}