#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef pair<int,pii> pip;
typedef vector<pip>vip;
const double PI=acos(-1);
const double EPS=1e-7;
const int inf=1e8;
const ll INF=1e16;
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};
int s,t,h;
vi used(30000);
vvi G(30000);
void f(int a){
	used[a]=true;
	t++;
	rep(i,G[a].size()){
		s++;
		int to=G[a][i];
		if(used[to])continue;
		f(to);
	}
}
int main(){
	int n;
	cin>>n;
	rep(i,n){
		int a,b,c,d;
		cin>>a>>b>>c>>d;
		G[a*200+b].pb(c*200+d);
		G[c*200+d].pb(a*200+b);
	}
	rep(i,30000)if(G[i].size()&&!used[i]){
		s=t=0;
		f(i);
		if(s/2>t)h=true;
	}
	if(!h)cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
}