#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
//#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
//#include<list>
#include<queue>
#include<deque>
#include<algorithm>
//#include<numeric>
#include<utility>
#include<complex>
//#include<memory>
#include<functional>
#include<cassert>
#include<set>
#include<stack>
#include<random>

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;

const int MAXN = 111;
pii from[MAXN], to[MAXN];
int color[2*MAXN];

void dfs(int v, int p, int& cnt, const vector<vi>& G) {
    color[v] = 1;
    for (int ch : G[v]) if (ch != p) {
        if (color[ch] == 2) continue;
        if (color[ch] == 1) {
            cnt++;
            continue;
        }
        dfs(ch, v, cnt, G);
    }
    color[v] = 2;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // input
    int N;
    cin >> N;
    assert(1 <= N && N <= 100);
    for (int i = 0; i < N; i++) {
        cin >> from[i].first >> from[i].second >> to[i].first >> to[i].second;
        assert(1 <= from[i].first && from[i].first <= 100);
        assert(1 <= from[i].second && from[i].second <= 100);
        assert(1 <= to[i].first && to[i].first <= 100);
        assert(1 <= to[i].second && to[i].second <= 100);
        assert(abs(to[i].first-from[i].first) + abs(to[i].second-from[i].second) == 1);
        assert(from[i].first < to[i].first || from[i].second < to[i].second);
    }
    for (int i = 0; i < N; i++) for (int j = i+1; j < N; j++) {
        assert(!(from[i] == from[j] && to[i] == to[j]));
    }
    // solve
    // まずわかりやすいグラフを作る
    map<pii, int> mp;
    for (int i = 0; i < N; i++) {
        mp[from[i]] = 0;
        mp[to[i]] = 0;
    }
    int k = 0;
    for (auto& el : mp) el.second = k++;
    vector<vector<int> > G(k);
    for (int i = 0; i < N; i++) {
        int u = mp[from[i]], v = mp[to[i]];
        G[u].push_back(v);
        G[v].push_back(u);
    }
    assert(k < 2*MAXN);
    // 貪欲 dfs
    for (int i = 0; i < k; i++) if (!color[i]) {
        int cnt = 0;
        dfs(i, -1, cnt, G);
        if (cnt >= 2) {
            cout << "NO" << endl;
            return 0;
        }
    }
    cout << "YES" << endl;
    return 0;
}