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 []x = new int[n];
        int []y = new int[n];
        for(int a = 0; a < n; a++){
             x[a] = in.nextInt();
             y[a] = in.nextInt();
        }
        int i;
        for( i=0;i<n-1;i++){
            if((x[i] == x[i+1]) | (y[i] == y[i+1])){
                continue;
            }
            else{
                break;
            }
        }
        if(i==n-1){
            System.out.println("YES");
        }
        else{
            System.out.println("NO");
        }
    }
}