#include <iostream>
#include <fstream>
#include <vector>

using namespace std;
int n,m;
//ifstream f;
vector <vector <int> > sz;
vector <int> foksz;
vector <int> zsak;
vector <bool> jo;
vector <int> cimke;

void bfs(int k)
{
    cimke.resize(n+1, -1);
    cimke[k] = 0;
    vector <int> sor;
    sor.push_back(k);
    while (!sor.empty())
    {
        int elso = sor.front();
        sor.erase(sor.begin());
        if(foksz[elso]<=2){
        for(int i = 0; i < sz[elso].size(); i++)
        {
            if(cimke[sz[elso][i]] == -1  )
            {
                cimke[sz[elso][i]] = cimke[elso] + 1;
                sor.push_back(sz[elso][i]);
            }
        }
        }
    }
}


int main()
{
   //f.open("graf.in");
   cin>>n>>m;
   foksz.resize(n+1);
   sz.resize(n+1);
   jo.resize(n+1,0);
   for(int i=1;i<=m;i++){
    int a,b;
    cin>>a>>b;
    sz[a].push_back(b);
    sz[b].push_back(a);
    foksz[a]++;
    foksz[b]++;
   }
   for(int i=1;i<=n;i++){
    if(foksz[i]==1){
        zsak.push_back(i);
    }
   }
    for(int i=0;i<zsak.size();i++){
         bfs(zsak[i]);
    }
    int db=0;
    for (int i = 1; i <= n; i++)
    {
        if(cimke[i]>0){
            db++;
        }
    }
    cout <<db<< endl;
    for (int i = 1; i <= n; i++)
    {
        if(cimke[i]>0){
            cout<<i<<" ";
        }
    }
}