#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin>>n;
	int a,b;
	cin>>a>>b;
	int count1=0;
	int count2=0;
	for(int i=1;i<n;i++)
	{
		int x,y;
		cin>>x>>y;
		if(x==a)
		count1++;
		else if(y==b)
		count2++;
	}
	if(count1==n-1 || count2==n-1)
	cout<<"YES"<<endl;
	else
	cout<<"NO"<<endl;
	return 0;
}