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 a0 = 0; a0 < n; a0++){
             x[a0] = in.nextInt();
             y[a0] = in.nextInt();
        }
        
       boolean found = true;
        int d = x[0];
        for(int i = 1;i<n;i++){
            if(d!=x[i]){
                found = false;
                break;
            }
        }
            
            if(!found){
                d = y[0];
        for(int i = 1;i<n;i++){
            if(d!=y[i]){
                found = false;
                break;
            }
            }
        }
            if(found){
                System.out.println("YES");
            }else{
                System.out.println("NO");
            }
    
}
}