#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <algorithm>
#include <cmath>
#include <iostream>
#include <map>

using namespace std;

int main() {
	int n;
	scanf("%d", &n);
	bool res = true;
	vector<pair<int, int>> v;
	for (int i = 0; i < n; i++) {
		int x, y;
		scanf("%d %d", &x, &y);
		v.push_back(make_pair(x, y));
	}
	sort(v.begin(), v.end());
	for (int i = 1; i < n; i++)
		res &= v[i].first == v[i - 1].first;
	if (!res) {
		res = true;
		for (int i = 1; i < n; i++)
			res &= v[i].second == v[i - 1].second;
	}
	printf("%s\n", res ? "YES" : "NO");
	return 0;
}