#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
vector<vector<pii>> graph;
stack<int> s;
vector<bool> ins;
void dfs(int i)
{
while (graph[i].size())
{
pii ele = graph[i].back();
graph[i].pop_back();
int r1 = ele.first;
int r2 = ele.second;
graph[r1][r2] = graph[r1].back();
graph[graph[r1][r2].first][graph[r1][r2].second].second = r2;
graph[r1].pop_back();
dfs(r1);
}
s.push(i);
if (ins[i])
{
do
{
ins[s.top()] = false;
cout << s.top()+1 << " ";
s.pop();
}
while (s.size() && s.top() != i);
cout << "\n";
}
ins[i] = true;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n, m;
cin >> n >> m;
graph = vector<vector<pii>>(n);
ins = vector<bool>(n, 0);
for (int i =0; i < m; i++)
{
int a, b;
cin >> a >> b;
a--; b--;
int sa = graph[a].size();
int sb = graph[b].size();
graph[a].push_back({b, sb});
graph[b].push_back({a, sa});
}
dfs(0);
return 0;
}
