#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using VI = vector<int>;
using VL = vector<ll>;
using PII = std::pair<int, int>;
using PLL = std::pair<ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define allpt(v) (v).begin(), (v).end()
#define allpt_r(v) (v).rbegin(), (v).rend()


const int mod = 1e9 + 7;
const string wsp = " ";
const string tb = "\t";
const string rt = "\n";

template <typename T>
void show1dvec(vector<T> v)
{
    int n = v.size() - 1;
    rep(i, n) cout << v[i] << wsp;
    cout << v[n] << rt;
    return;
}

template <typename T>
void show2dvec(vector<vector<T>> v)
{
    int n = v.size();
    rep(i, n) show1dvec(v[i]);
}

class Unionfind
{
    vector<int> p;

public:
    int find(int x);
    void unite(int x, int y);
    Unionfind(int n);
};

Unionfind::Unionfind(int n)
{
    for (int i = 0; i < n; i++)
    {
        p.push_back(i);
    }
}
int Unionfind::find(int x)
{
    while (p[x] != x)
    {
        p[x] = p[p[x]];
        x = p[x];
    }
    return x;
}

void Unionfind::unite(int x, int y)
{
    x = Unionfind::find(x);
    y = Unionfind::find(y);
    if (x != y)
    {
        p[x] = y;
    }
}

int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    int n, m, sa, sb, odd = 0;
    cin >> n >> m;
    Unionfind station(n);
    set<int> stationset, stationset2;
    VI deg(n);
    rep(i, m)
    {
        cin >> sa >> sb;
        station.unite(sa, sb);
        deg[sa]++, deg[sb]++;
        stationset.insert(sa), stationset.insert(sb);
    }
    for (auto z : stationset)
    {
        stationset2.insert(station.find(z));
        if (deg[z] % 2) odd++;
    }

    cout << ((stationset2.size() == 1 && (odd == 0 || odd == 2)) ? "YES" : "NO") << rt;


    return 0;
}