import java.util.*;
public class line {
	public static void main(String args[]){
		Scanner s= new Scanner(System.in);
		int n =s.nextInt();
		int a[]= new int[n];
		int b[]=new int[n];
		int flag1=0;
		int flag2=0;

		a[0]=s.nextInt();
		b[0]=s.nextInt();
		for(int i=1;i<n;i++){
			a[i]=s.nextInt();
			b[i]=s.nextInt();
			if(a[i]!=a[i-1])
				flag1=1;
			if(b[i]!=b[i-1])
				flag2=1;
		}
		if(flag1==0 || flag2==0)
			System.out.println("YES");
		else
			System.out.println("NO");
	}
}