#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define int long long
#define sz(a) (int)a.size()
#define all(a) begin(a),end(a)
const int mxN = (int)3e5+10;
int n, m;
int32_t main() {
cin >> n >> m;
for(int i = 0; i < m; i++){
int a, b; cin >> a >> b;
}
if(n<=m){
cout << "NO\n";
return 0;
}
cout << "YES\n";
if(n==1){
cout << "1\n1"; return 0;
}
if(n==2){
cout << "2\n1 1"; return 0;
}
cout << 2*(n-2) << "\n";
for(int i = 2; i <= n-1; i++) cout << i << " ";
for(int i = n-1; i >= 2; i--) cout << i << " ";
}
