using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static void Main(String[] args) {
        int n = int.Parse(Console.ReadLine());
        int[] X = new int[n], Y = new int[n];
        for (int i = 0; i < n; i++) {
            var tmp = Console.ReadLine().Split(' ');
            int l = int.Parse(tmp[0]);
            int r = int.Parse(tmp[1]);
            X[i] = l;
            Y[i] = r;
        }

        int ll = X[0], rr = Y[0];
        bool good = true;
        for (int i = 0; i < n; i++) {
            if (X[i] != ll) {
                good = false;
                break;
            }
        }
        if (good) { Console.WriteLine("YES"); } else {
            good = true;
            for (int i = 0; i < n; i++) {
                if (Y[i] != rr) {
                    good = false;
                    break;
                }
            }
            Console.WriteLine(good ? "YES":"NO");
        }
    }
}