#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define ff first
#define ss second
ll ttt;
const ll INF=1e18;
const ll MOD=1e9+7;
const ll N=300007;
ll n,m,k;
vector<ll>g[N];
ll sz[N];
bool used[N];
ll head[N];
void dfs(int v, int par=-1){
// cout<<"YOO"<<endl;
sz[v]=0;
for(int to:g[v]){
if(to!=par){
dfs(to,v);
sz[v]=max(sz[v],sz[to]+1);
}
}
}
bool is_tree(int c, int v, int par=-1){
used[v]=true;
head[v]=c;
bool retval=true;
for(int to:g[v]){
if(to!=par){
if(used[to])retval= false;
else if(!is_tree(c,to,v))retval= false;
}
}
return retval;
}
void construct(vector<int>& p, int v, int par=-1){
// cout<<"CONSTRUCT: "<<v<<" "<<par<<endl;
dfs(v);
// cout<<"SZ: ";
// for(int vv=1;vv<=n;vv++)cout<<sz[vv]<<" ";
// cout<<endl;
p.push_back(v);
int u=-1;
for(int to:g[v]){
if(to!=par){
if(sz[to]==1){
p.push_back(to);
p.push_back(v);
}
else if(sz[to]!=0) u=to;
}
}
if(u!=-1)construct(p,u,v);
}
int find_leaf(int v, int par=-1){
dfs(v);
for(int to:g[v]){
if(to!=par){
if(sz[to]>=2){
return find_leaf(to,v);
}
}
}
for(int to:g[v]){
if(sz[to]==1)return to;
}
return v;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
// freopen("output.txt","w",stdout);
// freopen("input.txt","r",stdin);
cin>>n>>m;
if(m!=n-1)cout<<"NO\n";
for(int i=0;i<m;i++){
int x,y;
cin>>x>>y;
g[x].push_back(y);
g[y].push_back(x);
}
for(int v=1;v<=n;v++){
if(!used[v]&&!is_tree(v,v)){
cout<<"NO\n";
return 0;
}
}
for(int v=1;v<=n;v++){
dfs(v);
int cnt=0;
for(int to:g[v]){
cnt+=(sz[to]>=2);
}
if(cnt>2){
cout<<"NO\n";
return 0;
}
}
cout<<"YES\n";
vector<int>p;
int leaf=find_leaf(1);
// cout<<"leaf: "<<leaf<<endl;
construct(p,leaf);
int len=p.size();
for(int i=len-1;i>=0;i--){
p.push_back(p[i]);
}
cout<<p.size()<<endl;
for(int x:p)cout<<x<<" ";
cout<<endl;
}
