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

#include <iostream>
#include <queue>
#include <algorithm>
#define ll long long
using namespace std;

struct adat {
    bool lat = false;
    vector<ll>sz;
};

vector<adat>x;
deque<ll>ans,v,zs;

ll i, n, m, akt, a, b;

void szelessegi(ll zsak)
{
    while (!v.empty())
    {
        akt = v.front();
        v.pop_front();
        for (auto& e : x[akt].sz)
        {
            if (!x[e].lat && e != zsak)
            {
                if (x[e].sz.size() <= 2)
                {
                    v.push_back(e);
                    ans.push_back(e);
                }
                else
                {
                    ans.push_back(e);
                    return;
                }
                x[e].lat = true;
            }
        }
    }
}

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)
        {
            v.push_back(i);
            zs.push_back(i);
            szelessegi(i);
        }
    }

    for (auto& e : zs)
    {
        if (x[e].lat)
        {
            ans.push_back(zs.front());
        }
    }

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

    cout << ans.size() << "\n";
    for (auto& e : ans)
    {
        cout << e << " ";
    }
}

/*
6 5
1 2
2 3
3 4
4 5
5 6
*/
// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

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