/**
 * Author: Sergey Kopeliovich (Burunduk30@gmail.com)
 */

#include <bits/stdc++.h>

using namespace std;

int n, m, a, b, u[1003];
vector<int> c[1003];

void dfs( int v ) {
  u[v] = 1;
  for (int x : c[v])
    if (!u[x])
      dfs(x), printf("%d %d\n", v, x);
}

int main() {
  cin >> n >> m;
  while (m--) {
    cin >> a >> b;
    c[a].push_back(b);
    c[b].push_back(a);
  }
  dfs(1);
  return 0;
}