#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)




int N;
set<int> vec;
vector<int> E[20101];
//-----------------------------------------------------------------
bool done[20101];
bool red[20101];
bool ans = true;
void dfs(int cur, int par) {
	done[cur] = true;
	for (int to : E[cur]) if (to != par && !done[to]) {
		if (!red[cur]) {
			red[cur] = true;
		}
		else {
			if (red[to]) {
				ans = false;
				return;
			}

			red[to] = true;
		}
	}

	for (int to : E[cur]) if (to != par && !done[to]) dfs(to, cur);
}
//-----------------------------------------------------------------
int main() {
	cin >> N;
	rep(i, 0, N) {
		int r0, c0, r1, c1;
		scanf("%d %d %d %d", &r0, &c0, &r1, &c1);
		r0--; c0--; r1--; c1--;

		int a = r0 * 150 + c0;
		int b = r1 * 150 + c1;
		vec.insert(a);
		vec.insert(b);
		E[a].push_back(b);
		E[b].push_back(a);
	}

	for (int i : vec) if (!done[i] && E[i].size() == 1) dfs(i, -1);

	if (ans)
		printf("YES\n");
	else
		printf("NO\n");
}