#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={0,1,-1,0,1,1,-1,-1,0};
const ll dx[9]={1,0,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

struct UnionFind {
    vector<int> par;
    vector<int> edge;
    
    UnionFind(int n) : par(n, -1),edge(n, 0) {}

    int root(int x) {
        if (par[x] < 0) return x;
        else return par[x] = root(par[x]);
    }
    
    bool same(int x, int y) {
        return root(x) == root(y);
    }
    
    bool merge(int x, int y) {
        x = root(x); y = root(y);
        if (x == y) {
            edge[x]++;
            return false;
        }
        if (par[x] > par[y]) swap(x, y);
        par[x] += par[y];
        par[y] = x;
        edge[x] += edge[y]+1;
        return true;
    }
    
    int size(int x) {
        return -par[root(x)];
    }
};


struct PotentialUF {
    vector<int> par;
    vector<int> edge;
    vector<ll> potential;
    PotentialUF(int n) : par(n, -1),edge(n, 0), potential(n,0) {}

    int root(int x) {
        if (par[x] < 0) return x;
        else{
          int r=root(par[x]);
          potential[x]+=potential[par[x]];
          return par[x] = r;
        } 
    }
    
    bool same(int x, int y) {
        return root(x) == root(y);
    }
    
    bool merge(int x, int y,ll w) {//yはxに比べてw大きい
        w+=weight(x);w-=weight(y);
        x = root(x); y = root(y);
        if (x == y) {
          edge[x]++;
          return false;
        }
        if (par[x] > par[y]) swap(x, y),w=-w;
        par[x] += par[y];
        par[y] = x;
        edge[x] += edge[y]+1;
        potential[y]=w;
        return true;
    }
    
    int size(int x) {
      return -par[root(x)];
    }
    ll weight(int x){
      root(x);
      return potential[x];
    }
    ll diff(int x,int y){//y-xを出力
      return weight(y)-weight(x);
    }
};

int main(){
    ll n,m;cin >> n >> m;
    UnionFind uf(n);
    vl deg(n);
    rep(i,m){
        ll a,b;cin >> a >> b;
        uf.merge(a,b);
        deg[a]++;deg[b]++;
    }
    ll com=0;
    ll odddeg=0;
    rep(i,n){
        if(deg[i]&1)odddeg++;
        if(uf.root(i)!=i)continue;
        if(uf.size(i)==1)continue;
        com++;
    }
    if(com>1||odddeg>2)cout << "NO" << endl,exit(0);
    cout << "YES" << endl;

}