#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define Rep(i,a,b) for(int i=a;i<b;i++)
#define ALL(x) (x).begin(),(x).end()
#define dbgv(x); for(auto now : x) cout << now << " "; cout << endl;

int x[3],y[3];
int dx[4] = {-1,0,1,0};
int dy[4] = {0,-1,0,1};
int main(){
    rep(i,3) cin >> x[i] >> y[i];
    double ans = 0;
    rep(ii,4)rep(jj,4)rep(kk,4){
        int xx[3],yy[3];
        vector<int> poses = {ii,jj,kk};
        rep(i,3) xx[i] = x[i]+dx[poses[i]];
        rep(i,3) yy[i] = y[i]+dy[poses[i]];
        rep(i,2) xx[i] -= xx[2];
        rep(i,2) yy[i] -= yy[2];
        cerr << xx[0] << " " << xx[1] << " " << yy[0] << " " << yy[1] << " " << (yy[1]-xx[0])*(yy[0]-xx[1])/2 << endl;
        cerr << ii << " " << jj << " " << kk << endl;
        double now = (double)((yy[1]*xx[0])-(yy[0]*xx[1]))/2;
        ans = max(ans,abs(now));
    }
    printf("%.8f\n",ans);
}