#include <bits/stdc++.h>

#define LL				long long
#define LD				long double
#define x				first
#define y 				second
#define NL				cout<<endl;
#define print_v(a)		for(vector<int>::iterator it=a.begin();it!=a.end();++it)cout<<*it<<"  ";
#define print(a,n)		for(int f=0;f<n;f++)cout<<a[f]<<"  ";
#define print2(a,n)		for(int f=0;f<n;f++){for(int g=0;g<n;g++)cout<<a[f][g]<<" ";NL}
#define print_p(a,n)	for(int f=0;f<n;f++)cout<<a[f].x<<"  "<<a[f].y<<endl;
#define pf(n)			cout<<n<<"  ";
#define all(a)			a.begin(),a.end()
#define s(n)			scanf("%d",&n);
#define sll(n)			scanf("%lld",&n);
#define sld(n)			scanf("%lf",&n);
#define ss(n)			scanf("%s",n);
#define pb(n)			push_back(n)
#define mp(a,b)			make_pair(a,b)
#define MOD				1000000009
#define N				100005
#define M 				1000006

using namespace std;

template <class T1, class T2>
struct sort_pair_second {
    bool operator()(const pair<T1,T2> &left, const pair<T1,T2> &right) {
        if(left.second < right.second)
    		return left.second < right.second;
        else if(left.second == right.second)
        	return left.first < right.first;
        return false;
    }
};


int main() {
	int n;
	cin >> n;
	
	int a,b,pa,pb;
	cin >> a >> b;
	cin >> pa >> pb;
	string ans="YES";
	n-=2;
	if(pa == a){
		while(n--){
			cin >> a >> b;
			if(a!=pa){
				ans = "NO";
				break;
			}
		}
	}else if(pb == b){
		while(n--){
			cin >> a >> b;
			if(b!=pb){
				ans = "NO";
				break;
			}
		}
	}else{
		ans = "NO";
	}
	
	cout << ans << endl;
}