#include <algorithm>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rrep(i, n) for (int i = (n)-1; i >= 0; i--)
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define mp make_pair
using namespace std;
typedef long long int lli;
lli MOD = 1000000007;
vector<int> e[100005];
vector<int> p[100005];
int f[100005];
int t[100005];

int main()
{
    int n, m;
    cin >> n >> m;
    int a, b;
    rep(i, m)
    {
        cin >> a >> b;
        a--, b--;
        e[a].push_back(b);
        e[b].push_back(a);
        f[i] = a, t[i] = b;
    }
    rep(i, e[0].size())
    {
        int in = e[0][i];
        rep(j, e[in].size())
        {
            if (e[in][j] != 0)
                p[e[in][j]].push_back(in);
        }
    }
    rep(i, m)
    {
        if (p[f[i]].size() == 0 || p[t[i]].size() == 0)
            continue;

        if (p[f[i]].size() != p[t[i]].size()) {
            cout << "YES" << endl;
            return 0;
        }
        bool flag[100005] = {};
        for (auto s : p[f[i]]) {
            if (s == t[i])
                continue;
            flag[s] = true;
        }
        for (auto s : p[t[i]]) {
            if (s == f[i])
                continue;

            if (!flag[s]) {
                cout << "YES" << endl;
                return 0;
            }
        }
    }
    cout << "NO" << endl;
}