#include <cmath>
#include <vector>
#include <map>
#include <functional>
#include <queue>
#include <iostream>
#include <string>
#include <iomanip>
#include <algorithm>
#include <functional>

using namespace std;

#define ll long long int
#define ti4 tuple<int,int,int,int>
#define pii pair<ll,ll>

static const int MAX_N = 100000;
vector<int> g[MAX_N];

struct hist
{
    int c;
    int v[5];
    
    bool ok(int n)
    {
        if(c != 5)
        {
            return false;
        }
        if(n == 1)
        {
            return true;
        }
        return false;
    }
    
    bool can(int n)
    {
        if(c >= 5)
        {
            return false;
        }
        for(int i = 0;i < c;i++)
        {
            if(v[i] == n)
            {
                return false;
            }
        }
        return true;
    }
    
    int last() const
    {
        return v[c-1];
    }
    
    hist add(int n)
    {
        hist next = *this;
        next.v[next.c] = n;
        next.c++;
        return next;
    }
};

int main()
{
    int n,m;
    cin >> n >> m;
    for(int i = 0;i < m;i++)
    {
        int f, s;
        cin >> f >> s;
        g[f].push_back(s);
        g[s].push_back(f);
    }
    queue<hist> q;
    q.push({1, 1});
    while(!q.empty())
    {
        auto s = q.front();
        q.pop();
        for(auto& r : g[s.last()])
        {
            if(s.ok(r))
            {
                cout << "YES" << endl;
                return 0;
            }
            if(!s.can(r))
            {
                continue;
            }
            q.push(s.add(r));
        }
    }
    cout << "NO" << endl;
    return 0;
}