#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <cstring>
#include <map>
#include <cstdlib>
#include <ctime>
#include <cassert>
#include <bitset>
#define f first
#define s second
#define ll long long
#define ull unsigned long long
#define mp make_pair
#define pb push_back
#define vi vector <int>
#define ld long double
#define pii pair<int, int>
using namespace std;    
const int N = int(3e5), mod = int(1e9)  + 7; 
int x,y,X,Y,n;

int main () {
	cin >> n;
	cin >> x >> y;
	bool f=  0,g = 0;
	for(int i=2;i<=n;i++){
		cin >> X >> Y;
		if(x != X) f = 1;
		if(y != Y) g = 1;
	}
	if(!f || !g) cout << "YES";
	else cout << "NO";

return 0;
}