/**
* 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;
}