#include<bits/stdc++.h>
using namespace std;
long long n, m, sum = 0;
vector<vector<long long>> g;
vector<long long> col, more;
int yno = 0;
int ans;
void dfs(int node, int dest, int &ways, vector<bool>vis) {
vis[node] = true;
if( node == dest && node ) ways++;
for( int i = 0; i < g[node].size(); i++) {
if( !vis[i]){
dfs( i, dest, ways, vis);
}
else if( vis[i] == true && i == node){
ways++;
return;
}
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin >> n >> m;
g.resize(n + 1);
col.resize(n + 1);
for( int i = 1; i <= m; i++)
{
long long a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
for( int i = 1; i <= n; i++)
{
if( g[i].size() == 1) ans = i;
for( int j = i + 1; i <= n; i++) {
int ways = 0;
vector<bool> vis(1005, false);
dfs(i, j, ways, vis);
if( ways > 1 ) {yno = 1; break;}
}
}
if( !yno ) {cout << "YES" << endl;
cout << 2 << endl;
cout << 1 << ' ' << ans;
}
else cout << "NO" << endl;
return 0;
}
