#include <algorithm>
#include <fstream>
#include <queue>
#include <set>
#include <vector>

using namespace std;

struct Nod
{
    int distanta;
    vector<int> vecini;
};

using Arbore = vector<Nod>;

void AflaDistante(Arbore &arb)
{
    vector<int> legaturi(arb.size(), 0);
    vector<bool> vizitat(arb.size(), false);
    queue<int> coada;

    for (unsigned i = 0; i < arb.size(); ++i) {
        legaturi[i] = arb[i].vecini.size();
        if (legaturi[i] == 1)
            coada.push(i);
        arb[i].distanta = 0;
    }

    while (!coada.empty()) {
        int nod = coada.front();
        coada.pop();

        vizitat[nod] = true;

        for (int v : arb[nod].vecini) {
            --legaturi[v];
            if (!vizitat[v])
                arb[v].distanta = max(arb[v].distanta, arb[nod].distanta + 1);
            if (legaturi[v] == 1)
                coada.push(v);
        }
    }
}

int AflaNodSalvare(const Arbore &arb, const set<int> &folosit)
{
    vector<pair<int, int>> dist_noduri;
    for (unsigned i = 1; i < arb.size(); ++i)
        dist_noduri.push_back({arb[i].distanta, i});
    sort(dist_noduri.begin(), dist_noduri.end(), greater<pair<int, int>>());

    for (auto &p : dist_noduri)
        if (folosit.find(p.second) == folosit.end())
            return p.second;
    return 0;
}

void Actualizeaza(Arbore &arb, int nod)
{
    queue<int> coada;
    coada.push(nod);
    arb[nod].distanta = 0;

    while (!coada.empty()) {
        nod = coada.front();
        coada.pop();

        for (int v : arb[nod].vecini) {
            if (arb[v].distanta > arb[nod].distanta + 1) {
                arb[v].distanta = arb[nod].distanta + 1;
                coada.push(v);
            }
        }
    }
}

pair<int, set<int>> AflaSalvari(Arbore &arb, int k)
{
    set<int> salvari;
    AflaDistante(arb);
    for (int i = 1; i <= k; ++i) {
        int nod = AflaNodSalvare(arb, salvari);
        salvari.insert(nod);
        Actualizeaza(arb, nod);
    }

    int tmax = 0;
    for (unsigned i = 1; i < arb.size(); ++i)
        tmax = max(tmax, arb[i].distanta);

    return {tmax + 1, salvari};
}

int main()
{
    ifstream fin("salvare.in");
    ofstream fout("salvare.out");

    int n, k;
    fin >> n >> k;

    Arbore arbore(n + 1);
    for (int i = 1; i < n; ++i) {
        int x, y;
        fin >> x >> y;
        arbore[x].vecini.push_back(y);
        arbore[y].vecini.push_back(x);
    }

    auto rez = AflaSalvari(arbore, k);
    fout << rez.first << "\n";
    for (int i : rez.second)
        fout << i << " ";

    return 0;
}