#include "iostream"
#include "vector"
using namespace std;

int main(int argc, char const *argv[])
{
	int n,f1=0,f2=0,a,b,a1,b1;
	cin>>n>>a1>>b1;
	for (int i = 0; i < n; ++i)
	{
		cin>>a>>b;
		if(a!=a1) f1=1;
		if(b!=b1) f2=1;

	}
	if(f1 && f2) cout<<"NO";
	else cout<<"YES";
	cout<<"\n";

	return 0;
}