#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
using namespace std;
using namespace __gnu_pbds;
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define mt make_tuple
#define mp make_pair
#define pb push_back
#define int long long
#define f first
#define s second
#define pll pair<long long, long long>
#define iii tuple<int,int,int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
signed main(){
int n,m;cin>>n>>m;
vector<vector<int>> al(n+1);
for(int i=0;i<m;i++){
int a,b;cin>>a>>b;
al[a].pb(b);
al[b].pb(a);
}
bool cycle=false;
vector<bool> vis(n+1, 0);
auto dfs=[&](auto && dfs, int x, int p)->void{
vis[x]=1;
for(auto it: al[x]){
if(it==p)continue;
if(vis[it]){
cycle=1;
return;
}
dfs(dfs, it, x);
}
};
dfs(dfs, 1, 0);
if(cycle)cout<<"NO";
else cout<<"YES\n1\n1";
}
