#include<iostream>
using namespace std;
int main(){
    int n,x,y,z,m=0,l=0;
    cin>>n;
    int a[n],b[n];
    for(int i=0;i<n;i++){
        cin>>a[i]>>b[i];
        if(a[i]==a[0]){
        	m=m+1;
		} 
		if(b[i]==b[0]){
			l=l+1;
		} 
       
    }
    if(m==n || l==n){
        cout<<"YES"<<endl;
    }
    else
        cout<<"NO";
    
    
        
}