#include<bits/stdc++.h>
using namespace std;
#define vi vector<int>
#define vvi vector<vi>
#define vs vector<string>
#define pb push_back
#define P pair<int,int>
#define vp vector<P>
#define PP pair<P,int>
#define vpp vector<PP>
#define fi first
#define se second
#define INF (1<<30)
#define MOD 1000000007
#define REP(i,n) for(int i=0;i<n;i++)
#define REPR(i,n) for(int i=n;i>=0;i--)
#define FOR(i,m,n) for(int i=m;i<n;i++)
#define all(x) (x).begin(),(x).end()
struct UnionFind{
    vi data;
    UnionFind(int size):data(size,-1){}
    bool unite(int x,int y){
        x=root(x);y=root(y);
        if(x!=y){
            if(data[y]<data[x])swap(x,y);
            data[x]+=data[y];data[y]=x;
        }
        return x!=y;
    }
    bool find(int x,int y){
        return root(x)==root(y);
    }
    int root(int x){
        return data[x]<0?x:data[x]=root(data[x]);
    }
    int size(int x){
        return -data[root(x)];
    }
};
int main(){
    int n,m;
    cin>>n>>m;
    vi vec(n);
    UnionFind uf(n);
    REP(i,m){
        int a,b;
        cin>>a>>b;
        vec[a]++;
        vec[b]++;
        uf.unite(a,b);
    }
    int cnt=0;
    REP(i,n){
        if(vec[i]%2)cnt++;
    }
    if(cnt==0||cnt==2){
        int k=0;
        set<int> se;
        REP(i,n){
            if(uf.size(i)==1)continue;
            else se.insert(uf.root(i));
        }
        if(se.size()==1)cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }else{
        cout<<"NO"<<endl;
    }
    return 0;
}