package no199;

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Vector2[] v = new Vector2[5];
		for(int i=0;i<5;i++) {
			v[i] = new Vector2(sc.nextInt(),sc.nextInt());
		}
		System.out.println(Vector2.convexHull(v).length == 5 ? "YES" : "NO");
	}
}
class Vector2 {
	int x = 0;
	int y = 0;
	public Vector2(int x,int y) {
		this.x = x;
		this.y = y;
	}
	public int dot(Vector2 v) {
		return this.x*v.x+this.y*v.y;
	}
	public int cross(Vector2 v) {
		return this.x*v.y-this.y*v.x;
	}
	public Vector2 add(Vector2 v) {
		return new Vector2(this.x+v.x,this.y+v.y);
	}
	public Vector2 subtract(Vector2 v) {
		return new Vector2(this.x-v.x,this.y-v.y);
	}
	public Vector2 multiply(int k) {
		return new Vector2(k*this.x,k*this.y);
	}
	public long normSquare() {
		return x * x + y * y;
	}
	public long distSquare(Vector2 v) {
		return this.subtract(v).normSquare();
	}
	public static Vector2[] convexHull(Vector2[] p) {
		int n = p.length;
		int k = 0;
		Arrays.sort(p,new LexicographicalComp());
		Vector2[] q = new Vector2[n*2];
		for(int i=0;i<n;q[k++]=p[i++]) {
			while(k >= 2 && q[k-2].subtract(q[k-1]).cross(q[k-1].subtract(p[i])) <= 0) {
				k--;
			}
		}
		for(int i=n-2, t=k+1;i>=0;q[k++]=p[i--]) {
			while(k >= t && q[k-2].subtract(q[k-1]).cross(q[k-1].subtract(p[i])) <= 0) {
				k--;
			}
		}
		return Arrays.copyOf(q, k-1);
	}
	public String toString() {
		return this.x + " " + this.y;
	}
	public static class LexicographicalComp implements Comparator<Vector2>{
		public int compare(Vector2 o1, Vector2 o2) {
			if (o1.x != o2.x) {
				return Integer.compare(o1.x, o2.x);
			}
			return Integer.compare(o1.y, o2.y);
		}
	}
}