#include <bits/stdc++.h>
using namespace std;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n, m;
cin >> n >> m;
if (m >= n) {
cout << "NO\n";
return 0;
}
const int maxn = 1000;
vector<int> adjlist[maxn];
for (int i = 0; i < m; i++) {
int a, b;
cin >> a >> b;
a--, b--;
adjlist[a].push_back(b), adjlist[b].push_back(a);
}
function<int(int, int)> dfs = [&](int cur, int par) {
int maxi = 0;
for (auto a : adjlist[cur])
if (a != par)
maxi = max(maxi, dfs(a, cur));
return maxi + 1;
};
for (int i = 0; i < n; i++) {
vector<int> vi;
for (auto a : adjlist[i])
vi.push_back(dfs(a, i));
int ct = 0;
for (auto a : vi) {
if (a >= 3)
ct++;
}
if (ct >= 2 && vi.size() >= 3) {
cout << "NO\n";
return 0;
}
}
cout << "YES\n1\n1\n";
}
