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

#define int long long

typedef pair<int,int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
template<class T,class U>void chmin(T &t,U f){if(t>f)t=f;}
template<class T,class U>void chmax(T &t,U f){if(t<f)t=f;}

struct bipartite_matching{
    static const int MAX_V=22222;
    vector<int>G[MAX_V];
    int match[MAX_V];
    bool used[MAX_V];

    void add_edge(int u,int v){
        G[u].push_back(v);
        G[v].push_back(u);
    }

    bool dfs(int v){
        used[v]=true;
        for(int i=0;i<G[v].size();i++){
            int u=G[v][i],w=match[u];
            if(w<0||!used[w]&&dfs(w)){
                match[v]=u;
                match[u]=v;
                return true;
            }
        }
        return false;
    }

    int matching(){
        int res=0;
        memset(match,-1,sizeof(match));
        for(int v=0;v<MAX_V;v++){
            if(match[v]<0){
                memset(used,0,sizeof(used));
                if(dfs(v))res++;
            }
        }
        return res;
    }
};



signed main(){
    bipartite_matching latte;
    int N;cin>>N;
    rep(i,N){
        int a,b,c,d;
        cin>>a>>b>>c>>d;
        a--;b--;c--;d--;
        latte.add_edge(10000+i,a*100+b);
        latte.add_edge(10000+i,c*100+d);
    }

    if(latte.matching()==N){
        cout<<"YES"<<endl;
    }
    else{
        cout<<"NO"<<endl;
    }
    return 0;
}