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

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

int N,M;
vint G[20000];

bool f[20000];
int A[50000],B[50000];

vint T[20000];

signed main(){
    cin>>N>>M;
    rep(i,M){
        int a,b;
        cin>>a>>b;
        a--;b--;
        G[a].pb(b);G[b].pb(a);
        A[i]=a;B[i]=b;
    }


    for(auto v:G[0])f[v]=true;


    rep(i,N)for(auto u:G[i]){
        if(f[u])T[i].pb(u);
    }

    rep(i,M){
        if(A[i]==1||B[i]==1)continue;
        for(int j=0;j<min((int)T[A[i]].size(),3ll);j++){
            for(int k=0;k<min((int)T[B[i]].size(),3ll);k++){
                int a=T[A[i]][j];
                int b=T[B[i]][k];
                if(a==B[i])continue;
                if(b==A[i])continue;
                if(a==b)continue;
                cout<<"YES"<<endl;
                return 0;
            }
        }
    }

    cout<<"NO"<<endl;
    return 0;
}