#include <bits/stdc++.h>
using ll = long long;
#define int ll
using namespace std;
#define sz(x) (int)(x).size()
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, l, r) for(int i = l; i >= r; i--)
#define fi first
#define se second
#define mod 998244353
#define db(x) cerr << __LINE__ << " " << #x << " " << x << "\n"
using vi = vector<int>;
using pi = pair<int, int>;
const ll N = 1005;
const ll inf = 1e18;
int n, m, par[N];
vi adj[N];
bool ok[N], used[N];
pi dfs(int u, int p = -1){
pi res(0, u);
for(auto &i : adj[u]){
if(i == p) continue;
par[i] = u;
pi j = dfs(i, u);
j.fi++;
res = max(res, j);
}
return res;
}
void solve(){
cin >> n >> m;
if(n == 1){
cout << "YES\n1\n1";
return;
}
if(n == 2){
cout << "YES\n2\n1 1";
return;
}
if(m != n - 1){
cout << "NO";
return;
}
foru(i, 1, m){
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
int x = dfs(1).se;
int y = dfs(x).se;
for(int i = y; ; i = par[i]){
ok[i] = true;
used[i] = true;
for(auto &j : adj[i]){
ok[j] = true;
for(auto &k : adj[j]){
ok[k] = true;
}
}
if(i == x) break;
}
if(count(ok + 1, ok + n + 1, 0)){
cout << "NO";
return;
}
vi res;
for(int i = par[y]; i != x; i = par[i]){
res.push_back(i);
for(auto &j : adj[i]){
if(used[j] or sz(adj[j]) == 1){
continue;
}
res.push_back(j);
res.push_back(i);
}
}
cout << "YES\n" << (sz(res) << 1) << "\n";
foru(i, 0, sz(res) - 1) cout << res[i] << " ";
ford(i, sz(res) - 1, 0) cout << res[i] << " ";
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
int t = 1;
while(t--){
solve();
}
}
