#include <bits/stdc++.h>
using namespace std;
vector<int> adj[1005];
vector<int> seq;
vector<bool> visited;
void dfs(int u, int p) {
seq.push_back(u);
visited[u] = true;
for (int v : adj[u]) {
if (!visited[v]) {
dfs(v, u);
seq.push_back(u); // backtrack step
}
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N, M;
cin >> N >> M;
for (int i = 0; i < M; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
// If M >= N, there must be a cycle (graph not a tree)
if (M >= N) {
cout << "NO\n";
return 0;
}
visited.assign(N + 1, false);
dfs(1, -1);
cout << "YES\n";
cout << seq.size() << "\n";
for (int i = 0; i < (int)seq.size(); i++) {
cout << seq[i] << (i + 1 == (int)seq.size() ? '\n' : ' ');
}
return 0;
}
