#include <bits/stdc++.h> 
using namespace std;

ifstream fin("arbore.in");
ofstream fout("arbore.out");

int n, m;
vector <int> g[100001];

int v[300001], k; 
int first[100001], last[100001];

int t[900001]; // Arbore de intervale
int aib[100001]; // Arbore indexat binar

void generate(int nod, int father)
{
    v[++k] = nod;
    first[nod] = k;

    for (auto& i : g[nod])
        if (i != father)
        {
            generate(i, nod);
            v[++k] = nod;
            last[nod] = k;
        }
}

void build(int i, int l, int r)
{
    if (l == r)
    {
        t[i];
        return;
    }

    int m = (l + r) / 2;

    build(2 * i, l, m);
    build(2 * i + 1, m + 1, r);
}

int main() 
{
    fin >> n >> m;

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

    generate(1, 0);

    return 0;
}