#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

double area(double x1, double x2, double x3, double y1, double y2, double y3){
	double xa = x2 - x1;
	double xb = x3 - x1;
	double ya = y2 - y1;
	double yb = y3 - y1;
	return abs(ya * xb - yb * xa) / double(2);
}

int main(){
	vector<double> x(3), y(3);
	rep(i,0,3) cin >> x[i] >> y[i];
	double ans = 0;
	for (auto[x1,y1]:{
		pair(x[0]+1,y[0]),
		pair(x[0]-1,y[0]),
		pair(x[0],y[0]-1),
		pair(x[0],y[0]+1)
	}){
		for (auto[x2,y2]:{
			pair(x[1]+1,y[1]),
			pair(x[1]-1,y[1]),
			pair(x[1],y[1]-1),
			pair(x[1],y[1]+1)
		}){
			for (auto[x3,y3]:{
				pair(x[2]+1,y[2]),
				pair(x[2]-1,y[2]),
				pair(x[2],y[2]-1),
				pair(x[2],y[2]+1)
			}){
				chmax(ans, area(x1,x2,x3,y1,y2,y3));
			}
		}
	}
	cout<<ans<<'\n';
}