#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define each(a, b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define pb push_back
#define show(x) cout <<#x<<" = "<<(x)<<endl
#define spair(p) cout <<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout <<" "<<kbrni;cout<<endl

using namespace std;

typedef pair<int,int>P;

const int MAX_N = 201;

map<P,int> mp;
vector<int> G[MAX_N];
bool flag[MAX_N];
vector<int> vec;
map<P,int> eda;

void dfs(int u)
{
    vec.pb(u);
    flag[u] = true;
    rep(i,G[u].size()){
        if(!flag[G[u][i]]){
            dfs(G[u][i]);
        }
    }
}

int main()
{
    int n;
    cin >> n;
    int cnt=0;
    rep(i,n){
        int a,b,c,d;
        cin >> a >> b >> c >> d;
        if(mp.count({a,b})==0){
            mp[{a,b}] = cnt++;
        }
        if(mp.count({c,d})==0){
            mp[{c,d}] = cnt++;
        }
        eda[{mp[{a,b}],mp[{c,d}]}]++;
        eda[{mp[{c,d}],mp[{a,b}]}]++;
        G[mp[{a,b}]].pb(mp[{c,d}]);
        G[mp[{c,d}]].pb(mp[{a,b}]);
    }
    rep(i,cnt){
        if(!flag[i]){
            vec.clear();
            dfs(i);
            int node = (int)vec.size();
            int edge = 0;
            rep(j,vec.size()){
                rep(k,vec.size()){
                    if(eda.count({vec[j],vec[k]})){
                        edge++;
                    }
                }
            }
            edge /= 2;
            if(edge >= node+1){
                cout << "NO\n";
                return 0;
            }
        }
    }
    cout << "YES\n";
    return 0;
}