#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int N, M;

void ok(){ puts("YES");exit(0); }

int main(){
    cin >> N >> M;
    vector<set<int> > es(N);
    vi adj(N), A(M), B(M);

    rep(i, M){
        scanf("%d%d", &A[i], &B[i]);
        --A[i]; --B[i];
        if(A[i] == 0)adj[B[i]] = 1;
        if(B[i] == 0)adj[A[i]] = 1;
    }

    rep(i, M){
        if(A[i] * B[i]){
            if(adj[A[i]])es[B[i]].insert(A[i]);
            if(adj[B[i]])es[A[i]].insert(B[i]);
        }
    }

    rep(i, M){
        int a = sz(es[A[i]]), b = sz(es[B[i]]);
        a -= (int)es[A[i]].count(B[i]);
        b -= (int)es[B[i]].count(A[i]);
        if(a == 1 && b == 1){
            each(u, es[A[i]])if(u != B[i])each(v, es[B[i]])if(v != A[i]){
                if(u != v)ok();
            }
        }
        if(a*b >= 2)ok();
    }
    puts("NO");
}