#include <bits/stdc++.h>
using namespace std;
using ll = long long;
// #define VERIFY
const int MAXN = 1001;
vector<int> g[MAXN], ans;
int n, m, md = 0, f = 0, cnt = 0, sz[MAXN];
void dfs(int u, int p = -1, int d = 0) {
if (md < d) {
md = d;
f = u;
}
for (int v : g[u]) {
if (v != p) dfs(v, u, d+1);
}
}
void dfs2(int u, int p = -1) {
if (cnt != n && g[u].size() != 1) ans.emplace_back(u);
cnt++;
for (int v : g[u]) {
if (v != p) {
dfs2(v, u);
if (cnt != n && ans.back() != u) ans.emplace_back(u);
}
}
}
int dfs3(int u, int p = -1) {
sz[u] = 1;
for (int v : g[u]) {
if (v != p) sz[u] = max(sz[u], dfs3(v, u)+1);
}
sort(g[u].begin(), g[u].end(), [&](int a, int b){
return sz[a] < sz[b];
});
return sz[u];
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
for (int i = 0; i < m; i++) {
int u, v; cin >> u >> v;
g[u].emplace_back(v);
g[v].emplace_back(u);
}
if (n - 1 != m) {
cout << "NO\n";
return 0;
}
bool ok = true;
for (int i = 1; i <= n; i++) {
int cnt = 0;
for (int u : g[i]) {
md = 0;
dfs(u, i);
cnt += md >= 2;
}
if (cnt >= 3) {
ok = false;
break;
}
}
cout << (ok ? "YES\n" : "NO\n");
if (n == 1) {
cout << "1\n1\n";
} else if (n == 2) {
cout << "2\n1 1\n";
} else if (ok) {
md = 0;
dfs(1);
dfs3(f);
dfs2(f);
vector<int> v;
for (int i : ans) v.emplace_back(i);
reverse(ans.begin(), ans.end());
for (int i : ans) v.emplace_back(i);
#ifdef VERIFY
assert(n <= 20);
int bits = (1<<n)-1;
for (int i : v) {
int nw = 0;
for (int j = 0; j < n; j++) {
if (i != j + 1 && bits & (1<<j)) {
for (int u : g[j+1]) {
nw |= 1<<(u-1);
}
}
}
bits = nw;
}
if (__popcount(bits) != 0) throw 1;
#endif
cout << v.size() << "\n";
for (int i : v) cout << i << " ";
cout << "\n";
}
return 0;
}
