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;

//highlight color RGB = [70,70,70]
#define asll unsigned long long
#define ll long long
#define ld long double
#define imt int
#define pii pair<int,int>
#define st first
#define nd second
#define kj <<" "<<
#define kjb <<" ";
#define dg <<","<<
#define ml <<endl;
#define co cout<<
#define ter cout<<endl;
#define sibi cout<<"TES"<<endl;
#define tes(x) cout<<"TES "<<x<<endl;
#define psbk(x) push_back(x);
#define For(x,a,b) for(int x=(a);x<(b);x++)
#define FOR(x,n) for(int x=0;x<(n);x++)
#define kera(x,m) for( int i = 0;i < m ; i++ ){ cout<<"x["<< i <<"] =" kj x[i] ml}
#define kpr(x) cout<<"("<<x.st dg x.nd <<")" ml
#define kkor(p) cout<<"("<<p.x dg p.y <<")" ml
#define m_p make_pair
asll M=1e9+7;
int n,m,tc;
int p,q,r;

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);cout.tie(0);
	srand(time(0));
	ll a[2],b[2];
	FOR(i,2){
		cin>>a[i];
	}
	FOR(i,2){
		cin>>b[i];
	}
	ll maks=-2e9-10;
	maks=max(max(a[0]*b[0],a[1]*b[0]),max(a[0]*b[1],a[1]*b[1]));
	/*
	FOR(i,2){
		FOR(j,2){
			if(1){
				//co a[i]*b[j] ml
				if(maks<a[i]*b[j]){
					maks=a[i]*b[j];
				}
				//maks=max(maks,);
				//maks=max(maks,b[i]*a[j]);
			}
		}
	}
	*/
	co maks ml
	
}