#include<stdio.h>
int main(){
	int n,i,j;
		int count=0;
			int count1=0;
	scanf("%d",&n);
	int x[n],y[n];
	for(i=0;i<n;i++){
		scanf("%d %d",&x[i],&y[i]);
	}
    for(i=1;i<n;i++){
		if(x[i]==x[i-1]){
		
			count++;
			
		}
		
	}

	  for(j=1;j<n;j++){
		if(y[j]==y[j-1]){
			
			count1++;
			
		}
		
	}

	if(count==n-1||count1==n-1){
		printf("YES");
	}
	else{
		printf("NO");
		
	}
	
	
	
	
}