import java.awt.Point;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class A {

	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	static StringTokenizer st;
	static PrintWriter out;

	public static String next() throws IOException {
		while (st == null || !st.hasMoreTokens()) {
			st = new StringTokenizer(br.readLine());
		}
		return st.nextToken();
	}

	public static int nextInt() throws IOException {
		return Integer.parseInt(next());
	}

	public static long nextLong() throws IOException {
		return Long.parseLong(next());
	}

	public static double nextDouble() throws IOException {
		return Double.parseDouble(next());
	}

	public static void main(String[] args) throws IOException {

		boolean res = true;
		boolean ok = true;

		int n = nextInt();

		Point[] t = new Point[n];

		t[0] = new Point(nextInt(), nextInt());

		for (int i = 1; i < n; i++) {
			t[i] = new Point(nextInt(), nextInt());
			if (i == 1) {
				if (t[i - 1].x == t[i].x) {
					ok = true;
				} else if (t[i - 1].y == t[i].y) {
					ok = false;
				} else {
					res = false;
					break;
				}
			} else if (ok) {
				if (t[i - 1].x != t[i].x) {
					res = false;
					break;
				}
			} else if (!ok) {
				if (t[i - 1].y != t[i].y) {
					res = false;
					break;
				}
			}
		}

		System.out.println(res ? "YES" : "NO");

	}

	static boolean tmp(Point p1, Point p2, Point p3) {
		return distBetween(p3, p1) == distBetween(p3, p2) + distBetween(p1, p2);
	}

	static double distBetween(Point p1, Point p2) {
		return Math.sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y));
	}

}