#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

class RollingHash
{
private:
    static const int X[], Y[], M[];
    long long hash[3];
public:
    RollingHash(){
        for(int i=0; i<3; ++i)
            hash[i] = 0;
    }
    void push_back(int a){
        for(int i=0; i<3; ++i){
            hash[i] *= X[i];
            hash[i] += a;
            hash[i] %= M[i];
        }
    }
    bool operator==(const RollingHash& rh) const{
        for(int i=0; i<3; ++i){
            if(hash[i] != rh.hash[i])
                return false;
        }
        return true;
    }
    bool operator!=(const RollingHash& rh) const{
        return !(*this == rh);
    }
};
const int RollingHash::X[] = {1685440109, 1389328937, 1813126193}; // 素数
const int RollingHash::Y[] = {1835226359, 1406652555,  643336582}; // X * Y == 1 (mod M)
const int RollingHash::M[] = {2000000087, 2000000089, 2000000099}; // 合同式の法（素数）


int main()
{
    int n, m;
    cin >> n >> m;

    vector<int> a(m), b(m);
    vector<vector<int> > edges(n);
    for(int i=0; i<m; ++i){
        cin >> a[i] >> b[i];
        -- a[i];
        -- b[i];
        edges[a[i]].push_back(b[i]);
        edges[b[i]].push_back(a[i]);
    }

    vector<set<int> > s(n);
    for(int x : edges[0]){
        for(int y : edges[x]){
            s[y].insert(x);
        }
    }

    for(int i=0; i<m; ++i){
        if(a[i] == 0 || b[i] == 0)
            continue;
        if(s[a[i]].empty() || s[b[i]].empty())
            continue;
        if(s[a[i]].size() == 1 && s[a[i]] == s[b[i]])
            continue;
        if(s[a[i]] == set<int>{ b[i] } || s[b[i]] == set<int>{ a[i] })
            continue;

        cout << "YES" << endl;
        return 0;
    }

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