#include <string>
#include <vector>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<stack>
#include<queue>
#include<cmath>
#include<algorithm>
#include<functional>
#include<list>
#include<deque>
#include<bitset>
#include<set>
#include<map>
#include<unordered_map>
#include<unordered_set>
#include<cstring>
#include<sstream>
#include<complex>
#include<iomanip>
#include<numeric>
#include<cassert>
#define X first
#define Y second
#define pb push_back
#define rep(X,Y) for (int (X) = 0;(X) < (Y);++(X))
#define reps(X,S,Y) for (int (X) = S;(X) < (Y);++(X))
#define rrep(X,Y) for (int (X) = (Y)-1;(X) >=0;--(X))
#define repe(X,Y) for ((X) = 0;(X) < (Y);++(X))
#define peat(X,Y) for (;(X) < (Y);++(X))
#define all(X) (X).begin(),(X).end()
#define rall(X) (X).rbegin(),(X).rend()
#define eb emplace_back
#define UNIQUE(X) (X).erase(unique(all(X)),(X).end())
#define Endl endl

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
template<class T> using vv=vector<vector<T>>;
template<class T> ostream& operator<<(ostream &os, const vector<T> &t) {
os<<"{"; rep(i,t.size()) {os<<t[i]<<",";} os<<"}"<<endl; return os;}
template<class S, class T> ostream& operator<<(ostream &os, const pair<S,T> &t) { return os<<"("<<t.first<<","<<t.second<<")";}
template<class T> inline bool MX(T &l,const T &r){return l<r?l=r,1:0;}
template<class T> inline bool MN(T &l,const T &r){return l>r?l=r,1:0;}
#define out(args...){vector<string> a_r_g_s=s_p_l_i_t(#args, ','); e_r_r(a_r_g_s.begin(), args); }
vector<string> s_p_l_i_t(const string& s, char c) { vector<string> v; stringstream ss(s); string x; while(getline(ss,x,c)) v.emplace_back(x); return move(v);}
void e_r_r(vector<string>::iterator it) {}
template<typename T, typename... Args> void e_r_r(vector<string>::iterator it, T a, Args... args){ if(*it==" 1"||*it=="1") cerr<<endl; else cerr << it -> substr((*it)[0] == ' ', it -> length()) << " = " << a << ", "; e_r_r(++it, args...);}
const ll MOD=1e9+7;
struct UF{
  vector<int> data;
  UF(int size):data(size,-1){}
  bool unite(int x,int y){
    x=root(x); y=root(y);
    if(x!=y){
      if(data[y]<data[x]) swap(x,y);
      data[x]+=data[y]; data[y]=x;
    }
    return x!=y;
  }
  bool findSet(int x,int y){return root(x)==root(y);}
  int root(int x){return data[x]<0?x:data[x]=root(data[x]);}
  int size(int x) {return -data[root(x)];}
};

int main(){
  ios_base::sync_with_stdio(false);
  cout<<fixed<<setprecision(0);
  int n;
  cin>>n;
  vector<pii> es(n);
  map<pii,int> id;
  rep(i,n){
    int a,b,c,d;
    cin>>a>>b>>c>>d;
    if(!id.count(pii(a,b))){int tmp=id.size();  id[pii(a,b)]=tmp;}
    if(!id.count(pii(c,d))){int tmp=id.size();  id[pii(c,d)]=tmp;}
    es[i]=pii(id[pii(a,b)], id[pii(c,d)]);
  }
  UF uf(id.size());
  for(pii p:es) uf.unite(p.X,p.Y);
  //for(pii p:es) out(p);out(1);
  vector<int> cnt(id.size());
  for(pii p:es) cnt[uf.root(p.X)]++;
  rep(i,id.size()) if(uf.root(i)==i){
    if(cnt[i]>uf.size(i)){
      cout<<"NO"<<endl;
      return 0;
    }
  }
  cout<<"YES"<<endl;
  return 0;
}