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

// #include<ext/pb_ds/assoc_container.hpp>
// #include<ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds; // find_by_order, order_of_key


#define IOS ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl "\n"
#define int long long


// int dx[4]={-1,0,1,0};
// int dy[4]={0,1,0,-1};

// int dx[8]={0,-1,-1,-1,0,1,1,1};
// int dy[8]={1,1,0,-1,-1,-1,0,1};

const int N = 200200;
const int mod = 1e9+7;
using ii = pair<int,int>;

//write on copy

int dx[5]={1,-1,0,0,0};
int dy[5]={0,0,0,1,-1};

double calc(ii a, ii b, ii c)
{
    double ans = 1.0*a.first*(b.second-c.second)+1.0*b.first*(c.second-a.second)+c.first*(a.second-b.second);
    return abs(ans)/2.0;
}

void solver(){
    vector<ii>arr;

    for(int i=0;i<3;i++)
    {
        int x,y;
        cin>>x>>y;

        arr.push_back({x,y});
    }

    double ans = 0;

    for(int i=0;i<5;i++)
    {
        for(int j=0;j<5;j++)
        {
            for(int k=0;k<5;k++)
            {
                int a = arr[0].first+dx[i];
                int b = arr[0].second+dy[i];

                int c = arr[1].first+dx[j];
                int d = arr[1].second+dy[j];

                int e = arr[2].first+dx[k];
                int f = arr[2].second+dy[k];

                ans = max(ans, calc({a,b},{c,d},{e,f}));
            }
        }
    }

    cout<<ans<<endl;

}


signed main()
{
    IOS
    //int _t;cin>>_t;while(_t--)
    solver();
    return 0;
}

#undef int