#include <bits/stdc++.h>
using namespace std;
vector<set<unsigned>> g;
vector<bool> visited;
void find_circuit(unsigned u, unsigned start_node)
{
if (visited[u] && u == start_node)
return;
cout << u + 1 << ' ';
visited[u] = 1;
for (unsigned const v : g[u])
{
if (!visited[v] || v == start_node)
{
g[u].erase(g[u].begin());
g[v].erase(u);
find_circuit(v, start_node);
break;
}
}
visited[u] = 0;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
size_t n, m;
cin >> n >> m;
g = vector<set<unsigned>>(n);
visited = vector<bool>(n, 0);
for (size_t i = 0; i < m; i++)
{
unsigned u, v;
cin >> u >> v;
g[u - 1].insert(v - 1);
g[v - 1].insert(u - 1);
}
for (unsigned u = 0; u < n; u++)
{
while (!g[u].empty())
{
find_circuit(u, u);
cout << '\n';
}
}
}
