#include <bits/stdc++.h>
using namespace std;

#define _p(...) (void)printf(__VA_ARGS__)
#define forr(x,arr) for(auto&& x:arr)
#define _overload3(_1,_2,_3,name,...) name
#define _rep2(i,n) _rep3(i,0,n)
#define _rep3(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,_rep3,_rep2,)(__VA_ARGS__)
#define _rrep2(i,n) _rrep3(i,0,n)
#define _rrep3(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define rrep(...) _overload3(__VA_ARGS__,_rrep3,_rrep2,)(__VA_ARGS__)
#define all(x) (x).begin(), (x).end()
#define bit(n) (1LL<<(n))
#define sz(x) ((int)(x).size())
#define fst first
#define snd second
using ll=long long;
using pii=pair<int,int>;using pll=pair<ll,ll>;using pil=pair<int,ll>;using pli=pair<ll,int>;
using vs=vector<string>;using vvs=vector<vs>;using vvvs=vector<vvs>;
using vb=vector<bool>;using vvb=vector<vb>;using vvvb=vector<vvb>;
using vi=vector<int>;using vvi=vector<vi>;using vvvi=vector<vvi>;
using vl=vector<ll>;using vvl=vector<vl>;using vvvl=vector<vvl>;
using vd=vector<double>;using vvd=vector<vd>;using vvvd=vector<vvd>;
using vpii=vector<pii>;using vvpii=vector<vpii>;using vvvpii=vector<vvpii>;
template<class T,class U>istream&operator>>(istream&is,pair<T,U>&P){is>>P.fst;is>>P.snd;return is;}
template<class T>T read(){T t;cin>>t;return t;}
template<class T,class U>ostream&operator<<(ostream&o,const pair<T,U>&p){return o<<'('<<p.fst<<", "<<p.snd<<')';}
template<class T>ostream&operator<<(ostream&o,const vector<T>&t){o<<"{";rep(i,sz(t))o<<t[i]<<",";o<<"}"<<endl;return o;}
vs s_p_l_i_t(const string&s,char c){vs v;stringstream ss(s);string x;while(getline(ss,x,c))v.emplace_back(x);return (v);}
void e_r_r(vs::iterator it){cerr<<endl;}
template<class T,class... Args>void e_r_r(vs::iterator it,T a,Args... args){cerr<<it->substr((*it)[0]==' ',it->length())<<" = "<<a<<", ";e_r_r(++it,args...);}
#define out(args...){vs a_r_g_s=s_p_l_i_t(#args,',');e_r_r(a_r_g_s.begin(),args);}

bool solve() {
  int n = read<int>();

  vi U(n), V(n);

  map<pii, int> P;
  int m = 0;

  rep(i, n) {
    int a = read<int>();
    int b = read<int>();
    int c = read<int>();
    int d = read<int>();

    if (P.count({a, b})) {
      U[i] = P[{a, b}];
    }
    else {
      U[i] = sz(P);
      P[{a, b}] = U[i];
    }

    if (P.count({c, d})) {
      V[i] = P[{c, d}];
    }
    else {
      V[i] = sz(P);
      P[{c, d}] = V[i];
    }
    m = max(m, max(U[i], V[i]) + 1);
  }

  vvi E(m);
  rep(i, n) {
    E[U[i]].push_back(V[i]);
    E[V[i]].push_back(U[i]);
  }

  //out(U, V);
  //out(E);
  //out(m);

  vb used(m);

  rep(i, m) if (used[i] == 0) {
    int uc = 0;
    function<void(int, int)> dfs = [&](int cur, int pre) {
      used[cur] = 1;
      forr(nex, E[cur]) {
        if (nex != pre) {
          if (used[nex]) uc++;
          else dfs(nex, cur);
        }
      }
    };
    dfs(i, -1);
    if (uc >= 2) return false;
  }

  return true;
}

void Main() {
  cout << (solve() ? "YES" : "NO") << endl;
}
int main() { cin.tie(nullptr); ios::sync_with_stdio(false); Main(); return 0; }