#include <bits/stdc++.h>
using namespace std;
const int N = 22;
int n, m, d[1 << N], adj[1 << N], par[1 << N];
void input() {
cin >> n >> m;
if (m != n - 1) {
cout << "NO\n";
exit(0);
}
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
u--, v--;
adj[1 << u] |= (1 << v);
adj[1 << v] |= (1 << u);
}
}
void solve() {
if (n == 1) {
cout << "YES\n" << 1 << '\n' << 1;
return;
}
for (int mask = 1; mask < (1 << n); mask++)
if (__builtin_popcount(mask) > 1)
adj[mask] = adj[mask - (mask & -mask)] | adj[mask & -mask];
memset(d, 63, sizeof d);
d[(1 << n) - 1] = 0;
queue<int> q;
q.push((1 << n) - 1);
while (!q.empty()) {
int u = q.front();
q.pop();
int tmp = adj[u];
for (int i = 0; i < n; i++)
if ((tmp >> i) & 1)
if (d[tmp ^ (1 << i)] > d[u] + 1) {
par[tmp ^ (1 << i)] = u;
d[tmp ^ (1 << i)] = d[u] + 1;
q.push(tmp ^ (1 << i));
}
}
if (d[0] > 1e9)
cout << "NO\n";
else {
cout << "YES\n" << d[0] << '\n';
vector<int> vec;
int p = 0;
while (p != (1 << n) - 1) {
vec.push_back(__builtin_ctz(adj[par[p]] ^ p));
p = par[p];
}
for (int i = vec.size() - 1; i >= 0; i--)
cout << vec[i] + 1 << ' ';
}
}
int main() {
ios:: sync_with_stdio(0), cin.tie(0), cout.tie(0);
input();
solve();
}
