#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(n);++i)
using namespace std;
using ll = long long;

double f(double x1, double y1, double x2, double y2, double x3, double y3) {
    double area = 0.5 * abs(x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2));
    return area;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int x1,y1,x2,y2,x3,y3;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    vector<int> dx = {1,-1,0,0};
    vector<int> dy = {0,0,1,-1};
    double ma = 0;
    rep(i,4){
        rep(j,4){
            rep(l,4){
                ma = max(ma,f(x1+dx[i],y1+dy[i],x2+dx[j],y2+dy[j],x3+dx[l],y3+dy[l]));
            }
        }
    }
    cout << ma << endl;
}