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 x1 = in.nextInt();
        int y1 = in.nextInt();
        
        boolean yes = true;
        
        for(int a0 = 1; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            
            if (yes && !(x == x1 || y == y1)) {
                yes = false;
            }
        }
        
        if (yes) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}