#include <bits/stdc++.h>
using namespace std;
const int N = 1e3 + 10;
int n, m;
vector<int> adj[N];
int dfs(int u, int par) {
int res = 0;
for (int v: adj[u])
if (v != par)
res = max(res, dfs(v, u) + 1);
return res;
}
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[u].push_back(v);
adj[v].push_back(u);
}
}
void solve() {
for (int i = 0; i < n; i++) {
int cnt = 0;
for (int v: adj[i])
cnt += (dfs(v, i) >= 2);
if (cnt > 2) {
cout << "NO\n";
return;
}
}
cout << "YES\n";
cout << n << '\n';
for (int i = 0; i < n; i++)
cout << 1 << ' ';
}
int main() {
ios:: sync_with_stdio(0), cin.tie(0), cout.tie(0);
input();
solve();
}
