//package practice;
import java.io.*;
import java.util.*;
class solution {
	static void print(Object o){
		System.out.println(o);
	}
	static void printnb(Object o){
		System.out.print(o);
	}
	public static void main(String[] args) throws Exception{
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] ar ;
		int i, j;
		int mod = 1000003;
		// ar = br.readLine().split(" ");
			int n = Integer.parseInt(br.readLine());
			//String regex = "( +)";
			//ar = br.readLine().split(regex);
			int[] a = new int[n];
			int[] b = new int[n];
			for(i=0;i<n;i++){
				ar = br.readLine().split(" ");
				int x = Integer.parseInt(ar[0]);
				int y = Integer.parseInt(ar[1]);
				a[i] = x;
				b[i] = y;
			}
			boolean ans1 = true;
			for(i=1;i<n;i++){
				if(a[i]!=a[i-1]){
					ans1 = false;
					break;
				}
			}
			boolean ans2 = true;
			for(i=1;i<n;i++){
				if(b[i]!=b[i-1]){
					ans2 = false;
					break;
				}
			}
			if(ans1 | ans2){
				print("YES");
			}
			else{
				print("NO");
			}
    }
}