#include <bits/stdc++.h>
using namespace std;
#define all(v) v.begin(), v.end()
typedef long long ll;
const int NMAX = 1e3 + 5;
int n, m, a, b, ix, mxd, er;
vector<int> adj[NMAX], ans;
void go(int x, int p, int d){
if(d > mxd){
mxd = d; ix= x;
}
for(int& nx : adj[x]){
if(nx == p) continue;
go(nx, x, d + 1);
}
return;
}
int dfs(int x, int p){
if(x == b) return 1;
int t = -1;
for(int& nx : adj[x]){
if(nx == p) continue;
if(dfs(nx, x)) {
t = nx; break;
}
}
if(t != -1){
ans.emplace_back(x);
for(int& nx : adj[x]){
if(nx == p) continue;
if(nx != t){
mxd = 0; go(nx, x, 1);
if(mxd >= 3) er = 1;
else if(mxd == 2) {
ans.emplace_back(nx);
ans.emplace_back(x);
}
}
}
}
return t != -1;
}
int solve(){
if(n <= 2) {
while(n--) ans.emplace_back(1);
return 1;
}
mxd = -1; go(1, -1, 0); b = ix;
mxd = -1; go(b, -1, 1); a = ix;
dfs(adj[a][0], a);
for(int i = ans.size() - 1; i >= 0; i--) ans.emplace_back(ans[i]);
return !er;
}
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m;
for(int i = 0; i < m; i++){
cin >> a >> b;
adj[a].emplace_back(b);
adj[b].emplace_back(a);
}
if(m == n - 1 && solve()) {
cout << "YES\n";
cout << ans.size() << '\n';
for(int& x : ans) cout << x << ' ';
}
else cout << "NO";
return 0;
}
