#include <bits/stdc++.h>
using namespace std;
int main(){
int n, m; cin >> n >> m;
vector<vector<pair<int, int>>> adj(n);
for( int i = 0; i < m; i++ ){
int a, b; cin >> a >> b;
a--; b--;
adj[a].push_back({ b, i });
adj[b].push_back({ a, i });
}
vector<int> marc(m), tour, in_tour(n);
function<void(int)> dfs = [&]( int cur ){
while( !adj[cur].empty() ){
auto [viz, id] = adj[cur].back(); adj[cur].pop_back();
if( marc[id] ) continue; marc[id] = true;
dfs( viz );
}
if( in_tour[cur] ){
cout << cur + 1 << " ";
while( in_tour[cur] ){
cout << tour.back() + 1 << " ";
in_tour[tour.back()] = false;
tour.pop_back();
}
cout << endl;
}
tour.push_back(cur);
in_tour[cur] = true;
};
dfs(0);
}
