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

using namespace std;

int n;
vector <int> G[100010];
queue <int> Q1, Q2;
bool viz[100010];

inline void Read()
{
    ifstream f ("nivele2.in");
    f>>n;
    int x, y;
    for (int i = 1; i<n; i++)
    {
        f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    f.close();
}

inline void Solve()
{
    ofstream g("nivele2.out");
    int x, nivel = 1;
    bool gata = false;
    vector <int>::iterator it;
    Q1.push(1);
    while (!gata)
    {
        g<<"nivelul "<<nivel<<":";
        while (!Q1.empty())
        {
            x = Q1.front();
            Q1.pop();
            viz[x] = true;
            g<<" "<<x;
            for (it = G[x].begin(); it!=G[x].end(); it++)
                if (viz[*it] == false)
                    Q2.push(*it);
        }
        while (!Q2.empty())
        {
            Q1.push(Q2.front());
            Q2.pop();
        }
        g<<"\n";
        if (Q1.empty())
            gata = true;
    }
    g.close();
}

int main()
{
    Read();
    Solve();
    return 0;
}