#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int main(){
    int n,count=0,cnt=0;
    scanf("%d\n",&n);
 
int A[n],B[n];
    for(int i = 0; i < n; i++) 
        scanf("%d %d\n",&A[i],&B[i]);
for(int j=0;j<n;j++){
if(A[j]==A[j+1])
 count=count + 1;
}
for(int p=0;p<n;p++){
 if(B[p]==B[p+1])
 cnt=cnt + 1;
}
if((count == n-1) || (cnt == n-1))
printf("YES\n");
else
printf("NO\n");
    return 0;
}