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 prevx = in.nextInt();
        int prevy = in.nextInt();
        for(int a0 = 0; a0 < n-1; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if (prevx != x && prevy != y) {
                System.out.println("NO");
                return;
            }
            prevx = x;
            prevy = y;
        }
        System.out.println("YES");
    }
}