#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int main(){
	vector < pair< int, int > > input;
	int n=0, in1=0, in2=0, cn1=1, cn2=1;
	cin>>n;

	while(n--){
		cin>>in1>>in2;
		input.push_back(make_pair(in1, in2));
	}

	in1 = input[0].first;
	in2 = input[0].second;

	for(unsigned int i=1; i<input.size(); i++){
		if(input[i].first == in1)
			cn1++;
		if(input[i].second == in2)
			cn2++;
	}
	n = input.size();
	if(cn1==n || cn2==n)	cout<<"YES\n";
	else	cout<<"NO\n";

return 0;
}