#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

/*================================*/

int N, M;

signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin >> N >> M;
    map<int, vector<int>> E;
    int a, b;
    REP(i, M) {
        cin >> a >> b;
        E[a].push_back(b);
        E[b].push_back(a);
    }
    
    int odds = 0;
    REP(i, N) if (E[i].size() % 2 == 1) odds++;
    if (odds > 2) {
        cout << "NO" << endl;
        return 0;
    }

    queue<int> q;
    q.push(a);
    while(!q.empty()) {
        int i = q.front();
        q.pop();
        for (auto j : E[i]) {
            q.push(j);
        }
        E[i].clear();
    }
    bool joined = true;
    REP(i, N) if (!E[i].empty()) joined = false;
    if (!joined) {
        cout << "NO" << endl;
        return 0;
    }
    
    cout << "YES" << endl;
    
    return 0;
}