#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);
}
if(n > 3){
cout<<"NO";
return 0;
}
else {
cout<<"YES\n";
cout<<min(n, 2ll)<<'\n';
for(int i=0;i<min(n, 2ll);i++)cout<<1<<' ';
}
}
