// Be nam KHODA
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define all(x) (x).begin(), (x).end()
#define F first
#define S second
const int N = 2e5 + 10, mod = 1e9 + 7, inf = INT_MAX;
int n, m;
vector<int> adj[N];
bool mark[N], cy;
int color[N];
void dfs(int u, int p = -1){
mark[u] = true;
if(p != -1) color[u] = color[p]^1;
for(auto & v : adj[u]){
if(mark[v] and color[u] == color[v])
cy = true;
if(!mark[v])
dfs(v, u);
}
}
int main(){
cin.tie(0), ios::sync_with_stdio(0);
cin >> n >> m;
for(int i = 0; i < m; i++){
int u, v;
cin >> u >> v;
u--, --v;
adj[u].push_back(v);
adj[v].push_back(u);
}
dfs(0);
if(cy)
cout << "NO" << endl;
else
cout << "YES\n1\n1" << endl;
return 0;
}
