#include <algorithm>
#include <iostream>
#include <cmath>
#include <cstring>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <vector>


#define MAX 50001

using namespace std;

int main() {
	int N, i;
	scanf("%d\n", &N);
	
	int H[N];
	int V[N];
	
	for(i=0;i<N;i++){
		scanf("%d %d\n", &H[i], &V[i]);
	}
	
	bool v=true, h=true;
	for(i=1;i<N;i++){
		if(H[i-1]!=H[i]) h= false;
		if(V[i-1]!=V[i]) v= false;
	}
	
	printf("%s\n", (v||h?"YES":"NO"));
	
	return 0;
}