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 buffx, buffy;
        buffx = in.nextInt();
        buffy = in.nextInt();
        boolean flag = true;
        for(int a0 = 1; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if((x==buffx) || (y==buffy)) {continue;}
            else {
                flag = false;
                break;
            }
        }
        if(flag)
            System.out.println("YES");
        else 
            System.out.println("NO");
        in.close();
    }
}