#include <bits/stdc++.h>
using namespace std;
const int MAX = 11;

int n, i;
int arr[MAX][2];
int main() {
	scanf("%d",&n);
	for(i = 0; i < n; i++) {
		scanf("%d %d",&arr[i][0],&arr[i][1]);
	}
	bool ans = true;
	for(i = 0; i < n; i++) {
		if(arr[i][0] == arr[i+1][0] || arr[i][1] == arr[i+1][1])
			continue;
		else {
			ans = false;
			break;
		}
	}
		
	if(ans) printf("YES\n");
	else printf("NO\n");
	return 0;
}