#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[101];
int vis[101];
bool ng;
void f(int u, int p) {
    vis[u] = 1;
    each(v, G[u])if(v != p) {
        if(vis[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;
    vi r0(N), c0(N), r1(N), c1(N);
    rep(i, N) {
        cin >> r0[i] >> c0[i] >> r1[i] >> c1[i];
    }
    rep(i, N) {
        auto p = mp(r0[i], c0[i]), q = mp(r1[i], c1[i]);
        rep(j, N) if(i!=j){
            auto r = mp(r0[j], c0[j]), s = mp(r1[j], c1[j]);
            if(p == r || p == s || q == r || q == s) {
                G[i].push_back(j);
            }
        }
    }
    ng = false;
    rep(i, N) {
        MEM(vis, 0);
        f(i, -1);
    }
    cout << (ng ? "NO" : "YES") << endl;
}