#include <iostream>
#include <vector>
#include <numeric>

using namespace std;

int par[202020];

int find(int x) {
	if (par[x] == x) return x;
	return par[x] = find(par[x]);
}

bool unite(int x, int y) {
	x = find(x);
	y = find(y);
	if (x == y) return false;
	par[x] = y;
	return true;
}

int main() {
	iota(par, par + 202020, 0);
	int n;
	cin >> n;
	vector<int> cycle(202020);
	for (int i = 0; i < n; i++) {
		int y1, x1, y2, x2;
		cin >> y1 >> x1 >> y2 >> x2;
		int u = y1 * 200 + x1;
		int v = y2 * 200 + x2;
		if (!unite(u, v)) {
			cycle[u]++;
		}
	}
	for (int i = 0; i < 202020; i++) {
		if (find(i) != i) {
			cycle[find(i)] += cycle[i];
		}
	}
	for (int i = 0; i < 202020; i++) {
		if (cycle[i] >= 2) {
			cout << "NO" << endl;
			return 0;
		}
	}
	cout << "YES" << endl;
}