import java.io.*;
import java.util.*;
public class Solution {

	public static void main(String[] args)throws IOException {
		// TODO Auto-generated method stub
		
		BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter outp = new PrintWriter(System.out);
		
		int n = Integer.parseInt(read.readLine().trim());
		
		int a[] = new int[n];
		int b[] = new int[n];
		for(int i=0;i<n;i++){
			String str[] = read.readLine().trim().split(" ");
			a[i] = Integer.parseInt(str[0]);
			b[i] = Integer.parseInt(str[1]);
		}
		int err = 0;
		for(int i=0;i<n;i++){
			if(a[0]!=a[i]){
				err = 1;
				break;
			}
		}
		if(err==1){
			err = 0;
			for(int i=0;i<n;i++){
				if(b[0]!=b[i]){
					err=1;
					break;
				}
			}
		}
		if(err==1){
			outp.println("NO");
		}
		else{
			outp.println("YES");
		}
		outp.close();

	}

}