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();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var map = NArr(4);
        for (var i = 0; i < 4; ++i)
        {
            map[i][0] *= 2;
            map[i][1] *= 2;
        }

        var p1 = Perpendicular(map[0], map[1]);
        var p2 = Perpendicular(map[1], map[2]);
        var p3 = Perpendicular(map[2], map[3]);
        var l1 = Line(p1.ra[0], p1.ra[1], p1.rb[0], p1.rb[1]);
        var l2 = Line(p2.ra[0], p2.ra[1], p2.rb[0], p2.rb[1]);
        var l3 = Line(p3.ra[0], p3.ra[1], p3.rb[0], p3.rb[1]);
        
        var c1 = Cross(l1.a, l1.b, l2.a, l2.b);
        var c2 = Cross(l2.a, l2.b, l3.a, l3.b);
        if (!c1.result || !c2.result)
        {
            WriteLine("NO");
            return;
        }
        WriteLine(Math.Abs(c1.x - c2.x) < 0.0001 && Math.Abs(c1.y - c2.y) < 0.0001 ? "YES" : "NO");
    }
    /// <summary>2点を通る直線 y = ax + b を返す</summary>
    static (double a, double b) Line(int ax, int ay, int bx, int by)
    {
        if (ax == bx) return (0, ax);
        var s = (double)(by - ay) / (bx - ax);
        return (s, ay - s * ax);
    }
    /// <summary>2直線の交点を求める 存在しないor無限に存在する場合false</summary>
    static (bool result, double x, double y) Cross(double a1, double b1, double a2, double b2)
    {
        if (a1 == a2) return (false, 0, 0);
        var x = (b2 - b1) / (a1 - a2);
        return (true, x, a1 * x + b1);
    }
    /// <summary>与えられた2点を通る垂線を通る2点を求める(各値は偶数である必要あり)</summary>
    /// <param name="a">点1</param>
    /// <param name="b">点2</param>
    /// <returns>垂線を通る2点</returns>
    static (int[] ra, int[] rb) Perpendicular(int[] a, int[] b)
    {
        var x = (a[0] + b[0]) / 2;
        var y = (a[1] + b[1]) / 2;
        return (new int[] { a[0] + x - y, a[1] + x + y }, new int[] { a[0] + x + y, a[1] + x - y });
    }
}