#include <bits/stdc++.h>
using namespace std;
vector<bool>vis;
vector<int>res;
vector<vector<pair<int,int>>>g;
void dfs(int a,int b)
{
while(!g[a].empty())
{
auto i=g[a].back();
if(vis[i.second])g[a].pop_back();
if(i.first!=b&&!vis[i.second])
{
g[a].pop_back();
vis[i.second]=true;
dfs(i.first,a);
}
}
res.push_back(a);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
int n,m,a,b;
cin>>n>>m;
vis.resize(m);
g.resize(n+1);
for(int i=0;i<m;i++)
{
cin>>a>>b;
g[a].push_back({b,i});
g[b].push_back({a,i});
}
dfs(1,1);
vector<bool>vis1(n+1);
vector<int>cont;
for(auto i:res)
{
if(vis1[i])
{
cout<<i<<" ";
while(cont.back()!=i)
{
cout<<cont.back()<<" ";
vis1[cont.back()]=false;
cont.pop_back();
}
cont.pop_back();
cout<<endl;
}
cont.push_back(i);
vis1[i]=true;
}
}
