#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
#define all(x) (x).begin(),(x).end()
#define X first
#define Y second
#define sep ' '
#define endl '\n'
#define debug(x) cerr << #x << ": " << x << endl;
const ll MAXN = 1e3 + 10;
int n, m, dist[MAXN], par[MAXN], D[MAXN];
vector<int> adj[MAXN], diam, ans;
void dfs(int v) {
dist[v] = dist[par[v]] + 1;
D[v] = 1;
for (int u : adj[v]) {
if (u != par[v]) {
par[u] = v;
dfs(u);
D[v] = max(D[v], D[u] + 1);
}
}
}
inline void add(int v) {
int m = ans.size();
if (m >= 2 && ans[m - 1] == v && ans[m - 2] == v) {
ans.pop_back();
ans.pop_back();
}
ans.push_back(v);
}
inline void dojob() {
int m = diam.size();
diam.push_back(-1);
int i = 0;
for (i = 0; i < m; i++) {
int v = diam[i];
add(v);
for (int u : adj[v]) {
if (u == par[v] || u == diam[i + 1]) continue;
if (D[u] >= 2) {
cout << "NO" << endl;
exit(0);
}
add(u);
add(v);
}
}
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> m;
if (m >= n) return cout << "NO" << endl, 0;
if (n == 1) return cout << "YES" << endl << 1 << endl << 1 << endl, 0;
if (n == 2) return cout << "YES" << endl << 2 << endl << 1 << sep << 1 << endl, 0;
for (int i = 1; i <= m; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
int rt = 0;
vector<int> vec;
for (int i = 1; i <= n; i++) {
if (adj[i].size() == 1)
vec.push_back(i);
else rt = i;
}
for (int e : vec)
for (int u : adj[e])
adj[u].erase(find(all(adj[u]), e));
dfs(rt);
int v = max_element(dist, dist + MAXN) - dist;
memset(par, 0, sizeof par);
memset(dist, 0, sizeof dist);
dfs(v);
v = max_element(dist, dist + MAXN) - dist;
while (v) {
diam.push_back(v);
v = par[v];
}
reverse(all(diam));
dojob();
int m = ans.size();
while (m--) ans.push_back(ans[m]);
cout << "YES" << endl << ans.size() << endl;
for (int e : ans) cout << e << sep;
cout << endl;
return 0;
}
