#include<bits/stdc++.h>
#define MAXN 600007
using namespace std;
int n,m,a,b,ver,cnt;
vector<int> v[MAXN];
vector<int> path;
bool dfs(int x,int p,int dep){
if(dep==1)return true;
for(int i:v[x]){
if(i==p)continue;
if(dfs(i,x,dep-1))return true;
}
return false;
}
void dfs2(int x,int p){
if(cnt<ver)path.push_back(x);
cnt++;
for(int i:v[x]){
if(i==p or v[i].size()==1)continue;
dfs2(i,x);
if(cnt<ver)path.push_back(x);
}
}
int main(){
cin>>n>>m;
for(int i=1;i<=m;i++){
cin>>a>>b;
v[a].push_back(b);
v[b].push_back(a);
}
if(m>n-1){
cout<<"NO\n";
return 0;
}
for(int i=1;i<=n;i++){
if(v[i].size()<=2)continue;
int br=0;
for(int f:v[i]){
if(dfs(f,i,3))br++;
}
if(br>2){
cout<<"NO\n";
return 0;
}
}
cout<<"YES\n";
if(n==1)cout<<"1\n1\n";
else if(n==2)cout<<"2\n1 1\n";
else{
for(int i=1;i<=n;i++){
if(v[i].size()>1)ver++;
}
ver=3*n;
for(int i=1;i<=n;i++){
if(v[i].size()==1)continue;
dfs2(i,0);
cout<<path.size()*2<<"\n";
for(int f:path)cout<<f<<" ";
//reverse(path.begin(),path.end());
for(int f:path)cout<<f<<" ";
cout<<"\n";
return 0;
}
}
return 0;
}
