#include<iostream>
#include<cmath>
#include<cstdio>
#include<algorithm>
using namespace std;
#include<stdio.h>
#define ll long long int
int main()
{
 ll n,i,j,c=0,h=0,v=0,r=1,x[100],y[100];
 cin>>n;
 for(i=0;i<n;i++)
 {
     cin>>x[i]>>y[i];
 }
 int f=1;
for(i=1;i<n;i++)
{
    if(x[i]!=x[i-1] && y[i]!=y[i-1])
    {
        f=0;
        break;
    }
}
if(f==1)
    cout<<"YES";
else
    cout<<"NO";
 return 0;
}