import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Main {
    private static boolean DEBUG = true;
    private static Scanner in;
    private static int N;
    private static int[] a, b;

    private static void preprocess() {
        // called before reading main input like queries and all.
    }

    private static void process() {
        // called for each set of main input.
    }

    public static void main(String[] args) {
        in = new Scanner(System.in);
        N = in.nextInt();
        a = new int[N];
        b = new int[N];
        for(int i=0;i<N;i++) {
            a[i] = in.nextInt();
            b[i] = in.nextInt();
        }
        boolean flag = true;
        int x = a[0];
        for(int i=1;i<N;i++) {
            if(a[i] != x) {
                flag = false;
                break;
            }
        }
        if(flag) {
            System.out.println("YES");
        } else {
            flag = true;
            x = b[0];    
            for(int i=1;i<N;i++) {
                if(b[i] != x) {
                    flag = false;
                    break;
                }
            }
            if(flag) {
                System.out.println("YES");
            } else {
                System.out.println("NO");
            }
        }
    }
}