#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define max(x,y) (x>y?x:y)
#define min(x,y) (x<y?x:y)
int cmp(const void *p,const void *q)
{
return *(int*)p-*(int*)q;
}
int main()
{
int n,i;
scanf("%d",&n);
int a[n][2],count1=0,count2=0;
for(i=0;i<n;i++)
{
scanf("%d %d",&a[i][0],&a[i][1]);
}
for(i=1;i<n;i++)
{
if(a[i][0]==a[i-1][0])
count1++;
else if(a[i][1]==a[i-1][1])
count2++;
else
break;
}
if(count1==n-1 || count2==n-1)
printf("YES");
else
printf("NO\n");
return 0;
}