#include <bits/stdc++.h>
#define MAX 101

int g[MAX][MAX], used[MAX];

using namespace std;

void dfs(int v, int n)
{

    int i;
    used[v] = 1;
    for(i = 1; i <= n; i++)
    {
        if (g[v][i] && !used[i])
        {
        printf("%d %d\n",v,i);
        dfs(i, n);
        }
    }
}

int main()
{
    int n, m;
    int a, b;
    scanf("%d %d",&n,&m);
    memset(g,0,sizeof(g)); memset(used,0,sizeof(used));

    while(m--)
    {
    scanf("%d %d",&a,&b);
    g[a][b] = g[b][a] = 1;
    }

    dfs(1, n);
}