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

public class Solution {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int firstTmp;
        int secondTmp;
        int fstLnFlag = 0;
        int sndLnFlag = 0;
        int[][] a;
        a = new int[n][2];
        
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            a[a0][0]=x;
            a[a0][1]=y;
        }
        
            firstTmp = a[0][0];
            secondTmp = a[0][1];
        
        for(int i = 0;i < n; i++){
            if(a[i][0] == firstTmp)
                {
                fstLnFlag++;
                firstTmp = a[i][0];
                }
            if(a[i][1] == secondTmp)
                {
                sndLnFlag++;
                secondTmp = a[i][0];
                }
        }
        if(fstLnFlag == n||sndLnFlag == n)
            {
            returnAnswer(true);
            }
        else{returnAnswer(false);}
        
    }
    public static void returnAnswer(Boolean a){
        if(a){
            System.out.println("YES");
        }
        else{
            System.out.println("NO");
        }
    }
}