// #pragma GCC target ("avx,avx2,fma")
// #pragma GCC optimize ("Ofast,inline") // O1 - O2 - O3 - Os - Ofast
// #pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b - 1); i >= (a); --i)
#define trav(a, x) for (auto &a : x)
#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define debug(x) cout << #x << " = " << x << endl
#define umap unordered_map
#define uset unordered_set
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;
const int INF = 1'000'000'007;
vi graph[1001];
int n, m, cnt, start;
bool dfs(int u, int p, int dist) {
//cout<<"u = "<<u+1<<" p = "<<p+1<<" dist = "<<dist<<endl;
if (dist == 3) return 1;
trav(v, graph[u]) if (v != p) {
bool val = dfs(v, u, dist + 1);
if(u==start)cnt+=val;
else if(val)return 1;
}
return 0;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit);
cin >> n >> m;
if (m >= n) {
cout << "NO" << endl;
return 0;
}
while (m--) {
int u, v;
cin >> u >> v;
graph[--u].pb(--v);
graph[v].pb(u);
}
rep(i, 0, n) {
cnt = 0;
start=i;
dfs(i, i, 0);
//cout << "u = " << i + 1 << " cnt = " << cnt << endl;
if (cnt >= 3) {
cout << "NO" << endl;
return 0;
}
}
cout << "YES\n1\n1" << endl;
return 0;
}
