package contest678;

import java.awt.geom.Line2D;
import java.util.*;

public class F {
	public static void main(String[] args) {
		new F().run();
	}

	void run() {
		solver();
	}

	void solver() {
//		Scanner sc = new Scanner(System.in);

//		int n = sc.nextInt();
//		int[][] qs = new int[n][];
//		for (int Q = 0; Q < n; ++Q) {
//			int t = sc.nextInt();// 0:add,1:removek,2:calc
//			if (t == 1) {
//				qs[Q] = new int[] { t, sc.nextInt(), sc.nextInt(), Q };
//			} else if (t == 2) {
//				qs[Q] = new int[] { t, sc.nextInt() - 1 };
//			} else if (t == 3) {
//				qs[Q] = new int[] { t, sc.nextInt() };
//			}
//		}
		Scanner sc = new Scanner(System.in);
		double[] x = new double[5];
		double[] y = new double[5];
		for (int i = 0; i < 5; i++) {
			x[i] = sc.nextDouble();
			y[i] = sc.nextDouble();
		}
		int[] d=convexHull(x, y);
		if(d.length==5){
			System.out.println("YES");
		}else{
			System.out.println("NO");
		}
	}

	int[] convexHull(final double[] x, final double[] y) {
		int n = x.length;
		Integer[] ord = new Integer[n];
		for (int i = 0; i < n; ++i) {
			ord[i] = i;
		}
		Arrays.sort(ord, new Comparator<Integer>() {
			@Override
			public int compare(Integer o1, Integer o2) {
				if (x[o1] != x[o2]) {
					return Double.compare(x[o1], x[o2]);
				} else {
					return Double.compare(y[o1], y[o2]);
				}
			}
		});

		int[] ret = new int[n + 1];
		int p = 0;
		for (int i = 0; i < n; ++i) {
			if (p >= 1 && x[ord[i]] == x[ret[p - 1]] && y[ord[i]] == y[ret[p - 1]])
				continue;
			while (p >= 2 && Line2D.relativeCCW(x[ret[p - 2]], y[ret[p - 2]], x[ret[p - 1]], y[ret[p - 1]], x[ord[i]],
					y[ord[i]]) == 1)
				p--;
			ret[p++] = ord[i];
		}

		int inf = p + 1;
		for (int i = n - 2; i >= 0; --i) {
			if (x[ret[p - 1]] == x[ret[i]] && y[ret[p - 1]] == y[ret[i]])
				continue;
			if (p >= inf && Line2D.relativeCCW(x[ret[p - 2]], y[ret[p - 2]], x[ret[p - 1]], y[ret[p - 1]], x[ord[i]],
					y[ord[i]]) == -1)
				p--;
			ret[p++] = ord[i];
		}

		return Arrays.copyOf(ret, p - 1);
	}
}