#include <cstdio>

#include <cmath>

#include <algorithm>

#include <iostream>

#include <cstring>

#include <queue>

#include <vector>

#define maxn 1250

#define INF  0x3f3f3f

using namespace std;

struct TwoSat{

    int n;

    vector<int> G[maxn*];

    bool mark[maxn*];

    int s[maxn*],cnt; 

    void init(int n){

        this->n = n;

        memset(mark,,sizeof(mark));

        for(int i=;i<n*;i++) G[i].clear();

    }

    bool dfs(int u){

        if(mark[u^]) return false;

        if(mark[u])   return true;

        mark[u] = true;

        s[cnt++] = u;

        for(int i=;i<G[u].size();i++){

            if(!dfs(G[u][i]))  return false;

        }

        return true;

    }

    void add_clause(int u,int uval,int v,int vval){ //这儿有问题

        u = u* + uval;    //u,v有矛盾；

        v = v* + vval;

        G[u].push_back(v^);

        G[v].push_back(u^);

    }

    bool solve(){

        for(int i=;i<n*;i+=){

            if(!mark[i] && !mark[i+]){  //为啥这个地方不回溯；

                cnt = ;

                if(!dfs(i)){

                    while(cnt > ) mark[s[--cnt]]  = false;

                    if(!dfs(i+)) return false;

                }

            }

        }

        return true;

    }

}solver;

int main()

{

    //freopen("input.txt","r",stdin);

    int n,m;

    while(scanf("%d%d",&n,&m)==){

        solver.init(n);

        for(int i=;i<=m;i++){

            int a,b,c,d;

            scanf("%d%d%d%d",&a,&b,&c,&d);

            solver.add_clause(a,c,b,d);

        }

        if(solver.solve())  printf("YES\n");

        else                printf("NO\n");

    }

}