#include<bits/stdc++.h>
using namespace std;
#include<stdio.h>
#include<string.h>
long long int i,j=0,k,l,m1,m2,m3,m4,m,n,a[100001],a1[10001]={0},a2[10001],mi=0,ma=0;
int main()
{
    cin>>n;
    m4=0,m3=0;
    for(i=1;i<=n;i++)
    {
        cin>>m1>>m2;
        if(i==1)
        {
            k=m1;
            l=m2;
        }
        else
            if(m1!=k)
            m3++;
        else
            if(m2!=l)
            m4++;
    }
    if(m3==0||m4==0)
        cout<<"YES\n";
        else
    cout<<"NO\n";
}