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 = 0, prevy = 0;
        for(int a0 = 0; a0 < n; a0++){
            int curx = in.nextInt();
            int cury = in.nextInt();
             
            if(a0 != 0){
                if(curx == prevx || cury == prevy) {
                } else{
                    System.out.println("NO");
                    return;
                }
            }
            prevx = curx;
            prevy = cury;
        }
        System.out.println("YES");
        
        
        
    }
}