#include <bits/stdc++.h>
using namespace std;
constexpr size_t N = 1000;
vector<size_t> g[N];
size_t adj_leafs[N];
void find_main_line(size_t u, size_t p, vector<size_t> &line)
{
line.push_back(u);
for (size_t v : g[u])
if (v != p && g[v].size() != 1)
{
find_main_line(v, u, line);
return;
}
}
int main()
{
size_t n, m;
cin >> n >> m;
if (m != n - 1)
{
cout << "NO\n";
return 0;
}
if (n == 1)
{
cout << "YES\n1\n1\n";
return 0;
}
if (n == 2)
{
cout << "YES\n2\n1 1\n";
return 0;
}
for (size_t i = 0; i < m; ++i)
{
size_t u, v;
cin >> u >> v;
g[u - 1].push_back(v - 1);
g[v - 1].push_back(u - 1);
}
for (size_t i = 0; i < n; ++i)
if (g[i].size() == 1)
adj_leafs[g[i][0]]++;
for (size_t i = 0; i < n; ++i)
if (g[i].size() > 1 && g[i].size() - adj_leafs[i] <= 1)
{
vector<size_t> line;
find_main_line(i, -1, line);
size_t num_non_leafs = 0;
for (size_t j = 0; j < n; ++j)
num_non_leafs += g[j].size() > 1;
if (line.size() != num_non_leafs)
{
cout << "NO\n";
return 0;
}
else
{
cout << "YES\n"
<< 2 * line.size() << '\n';
for (size_t u : line)
cout << u + 1 << ' ';
reverse(line.begin(), line.end());
for (size_t u : line)
cout << u + 1 << ' ';
cout << '\n';
return 0;
}
}
}
