#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define mt make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
#define pb push_back
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

vi G[201];
set<pii> fi;
vi r0, c0, r1, c1;
map<pii, int> p2i;
bool ng;
int vis[201], cnt[201];
void f(int u, int p) {
    if(ng)return;
    vis[u] = 1;
    each(v, G[u]) if(v != p) {
        if(vis[v] == 1) {
            cnt[v]++;
            if(cnt[v] > 1)ng = true;
        }
        if(!vis[v]) {
            f(v, u);
        }
    }
    vis[u] = 2;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N;
    cin >> N;
    r0 = c0 = r1 = c1 = vi(N);
    vi X, Y;
    rep(i, N) {
        cin >> r0[i] >> c0[i] >> r1[i] >> c1[i];
        X.pb(r0[i]);
        Y.pb(c0[i]);
        X.pb(r1[i]);
        Y.pb(c1[i]);
    }
    rep(i, 2 * N) {
        auto p = mp(X[i], Y[i]);
        if(!p2i.count(p)) {
            int m = sz(p2i);
            p2i[p] = m;
        }
    }
    rep(i, N) {
        pii p = mp(r0[i], c0[i]), q = mp(r1[i], c1[i]);
        G[p2i[p]].push_back(p2i[q]);
        G[p2i[q]].push_back(p2i[p]);
    }

    int M = sz(p2i);
    for(int i = 0; i < M; ++i) {
        MEM(vis, 0);
        MEM(cnt, 0);
        f(i, -1);
    }

    cout << (ng?"NO":"YES") << endl;
}