using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var mx = new int[] { 0, 0, -1, 1 };
        var my = new int[] { -1, 1, 0, 0 };
        var p1 = new int[] { c[0], c[1] };
        var p2 = new int[] { c[2], c[3] };
        var p3 = new int[] { c[4], c[5] };
        var ans = 0;
        for (var i = 0; i < 4; ++i) for (var j = 0; j < 4; ++j) for (var k = 0; k < 4; ++k)
        {
            p1[0] += mx[i];
            p1[1] += my[i];
            p2[0] += mx[j];
            p2[1] += my[j];
            p3[0] += mx[k];
            p3[1] += my[k];
            ans = Math.Max(ans, Tri(p1, p2, p3));
            p1[0] -= mx[i];
            p1[1] -= my[i];
            p2[0] -= mx[j];
            p2[1] -= my[j];
            p3[0] -= mx[k];
            p3[1] -= my[k];
        }
        WriteLine(ans / 2.0);
    }
    static int Tri(int[] p1, int[] p2, int[] p3)
    {
        return Math.Abs(F(p1, p2) + F(p2, p3) + F(p3, p1));
    }
    static int F(int[] p1, int[] p2)
    {
        return (p2[0] - p1[0]) * (p1[1] + p2[1]);
    }
}