#include <iostream>
#include <math.h>
//the highest product of three(negative numbers included)
using namespace std;

int fhighest(int current, int highest, int i)
{
	if (i == 0)
		highest = current;
	else
		highest = max(current, highest);
	return highest;
}

int flowest(int current, int lowest, int i)
{
	if (i == 0)
		lowest = current;
	else
		lowest = min(current, lowest);
	return lowest;
}

int fhighest_product_of_two(int highest_product_of_two, int current, int highest, int lowest, int i)
{
	if (i == 1)
		highest_product_of_two = max(current * highest, current * lowest);
	else
		if (i > 1)
			highest_product_of_two = max(highest_product_of_two, max(current * highest, current * lowest));
	return highest_product_of_two;
}

int flowest_product_of_two(int lowest_product_of_two,int current, int highest, int lowest, int i)
{
	if (i == 1)
		lowest_product_of_two = min(current * highest, current * lowest);
	else
		if (i > 1)
			lowest_product_of_two = min(lowest_product_of_two, min(current * highest, current * lowest));
	return lowest_product_of_two;
}

int fhighest_product_of_three(int highest_product_of_three, int current, int highest_product_of_two, int lowest_product_of_two, int i)
{
	if (i == 2)
		highest_product_of_three = max(current * highest_product_of_two, current * lowest_product_of_two);
	else
		if (i > 2)
			highest_product_of_three = max(highest_product_of_three, max(current * highest_product_of_two, current * lowest_product_of_two));
	return highest_product_of_three;
}


int main()
{
	int current;
	int highest_product_of_three = 0;
	int highest_product_of_two = 0;
	int highest = 0; 
	int lowest_product_of_two = 0;
	int lowest = 0;
	int i = 0;
	while(cin >> current)
	{
		highest_product_of_three = fhighest_product_of_three(highest_product_of_three, current, highest_product_of_two, lowest_product_of_two, i);
		highest_product_of_two = fhighest_product_of_two(highest_product_of_two, current, highest, lowest, i);
		lowest_product_of_two = flowest_product_of_two(lowest_product_of_two, current, highest, lowest, i);
		lowest = flowest(current, lowest, i);
		highest = fhighest(current, highest, i);
		i++;
	}

	cout << highest_product_of_three << endl;
	return 0;
}