using System;
using System.IO;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;

public class PointInt {
    public long X { get; set; }
    public long Y { get; set; }

    public PointInt() {

    }

    public PointInt(int x, int y) {
        this.X = x;
        this.Y = y;
    }

    public static PointInt operator +(PointInt p1, PointInt p2) {
        return new PointInt { X = p1.X + p2.X, Y = p1.Y + p2.Y };
    }

    public static PointInt operator -(PointInt p1, PointInt p2) {
        return new PointInt { X = p1.X - p2.X, Y = p1.Y - p2.Y };
    }

    public override bool Equals(object obj) {
        if (obj == null || GetType() != obj.GetType()) {
            return false;
        }
        var p = obj as PointInt;
        return this.X == p.X && this.Y == p.Y;
    }

    public override int GetHashCode() {
        return base.GetHashCode();
    }

    public long Norm {
        get {
            return 1L * X * X + 1L * Y * Y;
        }
    }

    public override string ToString() {
        return string.Format("({0},{1})", X, Y);
    }
}

public static class GeometryIntUtility {
    static public long CrossProduct(PointInt p1, PointInt p2) {
        return (long)p1.X * p2.Y - (long)p1.Y * p2.X;
    }

    static public int CCW(PointInt p1, PointInt p2, PointInt p3) {
        p2 -= p1;
        p3 -= p1;
        var cross = CrossProduct(p2, p3);
        if (cross > 0) return +1;
        if (cross < 0) return -1;
        if (p2.X * p3.X < 0 || p2.Y * p3.Y < 0) return +2;
        if (p2.Norm < p3.Norm) return -2;
        return 0;
    }

    static private void Traverse(List<PointInt> result, IEnumerable<PointInt> polygon, int t) {
        foreach (var p in polygon) {
            while (result.Count >= t
                && CCW(result[result.Count - 2], result[result.Count - 1], p) <= 0) {
                result.RemoveAt(result.Count - 1);
            }
            result.Add(p);
        }
    }

    static public List<PointInt> ConvexHull(List<PointInt> polygon) {
        int n = polygon.Count;
        if (n <= 3) return polygon.ToList();
        polygon.Sort((p1, p2) => {
            if (p1.Y != p2.Y) return p1.Y.CompareTo(p2.Y);
            return p1.X.CompareTo(p2.X);
        });
        var result = new List<PointInt>(2 * n);
        Traverse(result, polygon, 2);
        Traverse(result, polygon.AsEnumerable().Reverse(), result.Count + 1);
        result.RemoveAt(result.Count - 1);
        return result;
    }
}

partial class Solver {
    PointInt Read() {
        int x = ni();
        int y = ni();
        return new PointInt(x, y);
    }

    public void Run() {
        var points = Enumerable.Range(0, 5).Select(_ => Read()).ToArray();
        var convexPolygon = GeometryIntUtility.ConvexHull(points.ToList());
        cout.WriteLine(convexPolygon.Count == 5 ? "YES" : "NO");
    }
}

// PREWRITEN CODE BEGINS FROM HERE
partial class Solver : Scanner {
    public static void Main(string[] args) {


        new Solver(Console.In, Console.Out).Run();
    }

    TextReader cin;
    TextWriter cout;

    public Solver(TextReader reader, TextWriter writer)
        : base(reader) {
        this.cin = reader;
        this.cout = writer;
    }
    public Solver(string input, TextWriter writer)
        : this(new StringReader(input), writer) {
    }

    public int ni() {
        return NextInt();
    }
    public long nl() {
        return NextLong();
    }
    public string ns() {
        return Next();
    }
}

public class Scanner {
    private TextReader Reader;
    private Queue<String> TokenQueue = new Queue<string>();
    private CultureInfo ci = CultureInfo.InvariantCulture;

    public Scanner()
        : this(Console.In) {
    }

    public Scanner(TextReader reader) {
        this.Reader = reader;
    }

    public int NextInt() { return Int32.Parse(Next(), ci); }
    public long NextLong() { return Int64.Parse(Next(), ci); }
    public double NextDouble() { return double.Parse(Next(), ci); }
    public string[] NextArray(int size) {
        var array = new string[size];
        for (int i = 0; i < size; i++) array[i] = Next();
        return array;
    }
    public int[] NextIntArray(int size) {
        var array = new int[size];
        for (int i = 0; i < size; i++) array[i] = NextInt();
        return array;
    }

    public long[] NextLongArray(int size) {
        var array = new long[size];
        for (int i = 0; i < size; i++) array[i] = NextLong();
        return array;
    }

    public String Next() {
        if (TokenQueue.Count == 0) {
            if (!StockTokens()) throw new InvalidOperationException();
        }
        return TokenQueue.Dequeue();
    }

    public bool HasNext() {
        if (TokenQueue.Count > 0)
            return true;
        return StockTokens();
    }

    private bool StockTokens() {
        while (true) {
            var line = Reader.ReadLine();
            if (line == null) return false;
            var tokens = line.Trim().Split(" ".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
            if (tokens.Length == 0) continue;
            foreach (var token in tokens)
                TokenQueue.Enqueue(token);
            return true;
        }
    }
}