import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
import java.util.Map.Entry;

public class _483 {
	public static void main(String[] args) throws IOException {
		new _483().solve();
	}

	void solve() throws IOException {
		try (final Scanner in = new Scanner(System.in)) {
			int n = in.nextInt();
			TreeMap<Integer, TreeSet<Integer>> g = new TreeMap<>();
			for (int i = 0; i < n; i++) {
				int x1 = in.nextInt();
				int y1 = in.nextInt();
				int x2 = in.nextInt();
				int y2 = in.nextInt();
				int k1 = x1 * 200 + y1;
				int k2 = x2 * 200 + y2;
				TreeSet<Integer> es1 = g.getOrDefault(k1, new TreeSet<>());
				TreeSet<Integer> es2 = g.getOrDefault(k2, new TreeSet<>());
				es1.add(k2);
				es2.add(k1);
				g.put(k1, es1);
				g.put(k2, es2);
			}
			TreeMap<Integer, Integer> deg = new TreeMap<>();
			for (Entry<Integer, TreeSet<Integer>> e : g.entrySet()) {
				deg.put(e.getKey(), e.getValue().size());
			}
			while (true) {
				TreeSet<Integer> ks = new TreeSet<>(g.keySet());
				boolean updated = false;
				boolean all2 = true;
				for (int k : ks) {
					all2 &= g.get(k).size() == 2 || g.get(k).size() == 0;
					if (g.get(k).size() == 1) {
						g.get(g.get(k).first()).remove(k);
						g.remove(k);
						updated = true;
					}
				}
//				dump(all2, updated);
				if (!updated) {
					System.out.println(all2 ? "YES" : "NO");
					break;
				}
			}
		}
	}
	
	// for debug
	static void dump(Object... o) {
		System.err.println(Arrays.deepToString(o));
	}
}