#include <bits/stdc++.h>
using namespace std;
long long n, m;
vector<vector<long long>> g;
int par[1005], h[1005], path[1005];
vector<int> ans;
pair<int, int> dfs(int node, int parent) {
int maxd = 0;
int distm = node;
for (auto it : g[node]) {
if (it != parent) {
par[it] = node;
auto s = dfs(it, node);
s.first++;
if (s.first > maxd) {
maxd = s.first;
distm = s.second;
}
}
}
return {maxd, distm};
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin >> n >> m;
g.resize(n + 1);
if (m != n - 1) {
cout << "NO";
return 0;
}
for (int i = 1; i <= m; i++) {
long long a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
int u = dfs(1, -1).second;
int v = dfs(u, -1).second;
int curr = v;
while (curr != u) {
path[curr] = h[curr] = 1;
for (auto it : g[curr]) {
h[it] = 1;
for (auto ed : g[it]) {
h[ed] = 1;
}
}
curr = par[curr];
}
h[u] = 1;
bool isUnvisited = false;
for (int i = 1; i <= n; i++) {
if (h[i] == 0) {
isUnvisited = true;
break;
}
}
if (isUnvisited) {
cout << "NO" << endl;
return 0;
}
int cur = par[v];
while (cur != u) {
ans.push_back(cur);
for (auto it : g[cur]) {
if (g[it].size() == 1 || path[it]) continue;
ans.push_back(it);
ans.push_back(cur);
}
cur = par[cur];
}
cout << "YES" << endl;
cout << 2 * ans.size() << endl;
for (int x : ans) cout << x << " ";
reverse(ans.begin(), ans.end());
for (int x : ans) cout << x << " ";
cout << endl;
return 0;
}
