import java.util.Scanner;

class point{
	
	public static void main(String ar[]){



		int n,j,c1=1,c2=1;
		Scanner ob=new Scanner(System.in);
		n=ob.nextInt();
		int a1[]=new int[n];
		int a2[]=new int[n];

		for(int i=0;i<n;i++){
			a1[i]=ob.nextInt();
			a2[i]=ob.nextInt();
		}
		for (j=0;j<n-1;j++) {
			if(a1[j]==a1[j+1]){
				c1++;
			}
			if(a2[j]==a2[j+1]){
				c2++;
			}
		}
		if(c1==n || c2==n){
System.out.println("YES");
		}else{
			System.out.println("NO");
		}

		
	}
}