#include <bits/stdc++.h>
using namespace std;
#define forsn(i, s, n) for (int i = int(s); i < int(n); i++)
#define forn(i, n) forsn(i, 0, n)
#define dforsn(i, s, n) for (int i = int(n) - 1; i >= int(s); i--)
#define dforn(i, n) dforsn(i, 0, n)
#define foreach(it, c) for (auto it = begin(c); it != end(c); it++)
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define fst first
#define snd second
#define pb push_back
#define eb emplace_back
using ll = long long;
using vll = vector<ll>;
using vi = vector<int>;
using ii = pair<int, int>;
const int INF = 1e9;
const int MAX_N = 1005;
int maxDepth[MAX_N];
vi adj[MAX_N];
int dfs0(int u, int p = -1) {
int maxi = 0;
for (int v : adj[u]) if (v != p) {
maxi = max(maxi, dfs0(v,u) + 1);
}
return maxDepth[u] = maxi;
}
int dist[MAX_N], par[MAX_N];
void dfs(int u) {
for(int v : adj[u]) if (v != par[u]){
par[v] = u, dist[v] = dist[u] + 1;
dfs(v);
}
}
bool check(int n, int m) {
if (m != n - 1) return false;
forn(u,n){
int cnt = 0;
for (int v : adj[u]){
if (dfs0(v, u) >= 2) cnt++;
}
if (cnt > 2) return false;
}
return true;
}
int findFurthest(int s, int n) {
par[s] = -1, dist[s] = 0;
dfs(s);
int u = 0;
forn(v, n) {
if (dist[v] > dist[u]) u = v;
}
return u;
}
vi findDiameter(int n){
int u = findFurthest(0, n);
int v = findFurthest(u, n);
vi diameter{v};
while (diameter.back() != u) {
diameter.pb(par[diameter.back()]);
}
return diameter;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n, m;
cin >> n >> m;
forn(i, m) {
int u, v;
cin >> u >> v;
--u, --v;
adj[u].pb(v);
adj[v].pb(u);
}
if (!check(n, m)) {
cout << "NO\n";
return 0;
}
cout << "YES\n";
if (n <= 2) {
cout << n << '\n';
forn(i, n) cout << "1 ";
cout << '\n';
return 0;
}
vi d = findDiameter(n);
vi ret;
forsn(i, 1, sz(d) - 1) {
int u = d[i];
ret.pb(u);
for(int v : adj[u]) if (sz(adj[v]) != 1 && v != d[i + 1] && v != d[i - 1]) {
ret.pb(v), ret.pb(u);
}
}
cout << 2 * sz(ret) << '\n';
forn(i, sz(ret)) cout<< ret[i] + 1 << ' ';
dforn(i, sz(ret)) cout << ret[i] + 1 << ' ';
cout << '\n';
return 0;
}
