// elagaz.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

struct adat
{
    bool lat;
    int tav;
    vector <int> sz;
};

vector <int> v;
vector <adat> x;
long long n, i, m, a, b;

void mely(int csp, int kezd)
{
    x[csp].lat = 1;
    v.push_back(csp);

    if (x[csp].sz.size() == 2)
    {
        for (auto& e : x[csp].sz)
        {
            if (x[e].lat == 0 && kezd!=e)
            {
                x[e].lat = 1;
                mely(e, kezd);
            }
        }
    }
}

int main()
{
    cin >> n >> m;
    x.resize(n + 1);

    for (i = 1; i <= m; ++i)
    {
        cin >> a >> b;
        x[a].sz.push_back(b);
        x[b].sz.push_back(a);
    }

    for (i = 1; i <= n; ++i)
    {
        if (x[i].sz.size() == 1)
        {
            mely(x[i].sz[0], i);
        }
    }

    cout << v.size() << "\n";

    sort(v.begin(), v.end());

    for (auto& e : v) cout << e << " ";

    return 0;
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

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