#include<bits/stdc++.h>

using namespace std;

struct I{I(){ios::sync_with_stdio(false);cin.tie(0);}}init;

typedef vector<int> V;
typedef vector<V> Graph;

void check(int N,int M,V A,V B){
    assert(2<=N&&N<=20000);
    assert(0<=M&&M<=min(N*(N-1)/2,50000));
    using P=pair<int,int>;
    set<P> s;
    for(int i=0;i<M;i++){
        assert(A[i]!=B[i]);
        P p(min(A[i],B[i]),max(A[i],B[i]));
        assert(s.count(p)==0);
        s.insert(p);
    }
}


int main(){
    int N,M;
    cin>>N>>M;
    vector<int> A(M),B(M);
    for(int i=0;i<M;A[i]--,B[i]--,i++)cin>>A[i]>>B[i];
    check(N,M,A,B);
    Graph g(N);
    for(int i=0;i<M;i++){
        g[A[i]].push_back(B[i]);
        g[B[i]].push_back(A[i]);
    }

    vector<bool> near(N,false);
    for(auto &v:g[0])near[v]=true;
    vector<set<int>> V(N);
    for(int i=0;i<M;i++){
        int x=A[i],y=B[i];
        if(near[x]&&V[y].size()<3)V[y].insert(x);
        swap(x,y);
        if(near[x]&&V[y].size()<3)V[y].insert(x);
    }
    for(int i=0;i<M;i++){
        int x=A[i],y=B[i];
        if(x*y>0)
            for(auto &s:V[x])
                for(auto &t:V[y])
                    if(s!=t&&s!=y&&t!=x){
                        cout<<"YES"<<endl;
                        return 0;
                    }
    }
        
    cout<<"NO"<<endl;
    return 0;
}