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 a = in.nextInt();
            int b = in.nextInt();
        int fl =0, fy =0;
        for(int a0 = 0; a0 < n-1; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(a != x){
                fl = 1;
            }
            if(b != y){
                fy = 1;
            }
        }
        
        if(fl == 0 || fy == 0){
            System.out.println("YES");
        }
        else{
            System.out.println("NO");
        }
    }
}