#include <bits/stdc++.h>
using namespace std;
vector<vector<int>>g;
vector<pair<int,int>>edges;
vector<bool>vis,vis1;
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n,m,a,b;
    cin>>n>>m;
    vis1.resize(n+1);
    vis.resize(m);
    g.resize(n+1);
    for(int i=0;i<m;i++)
    {
        cin>>a>>b;
        g[a].push_back(i);
        g[b].push_back(i);
        edges.push_back({a,b});
    }
    vector<int>res;
    int sum=0;
    a=1;
    bool check=true;
    for(int j=1;j<=n;j++)
    {
        int sum=0;
        for(auto i:g[a])if(!vis[i])sum++;
        if(!sum)continue;
        sum=sum/2;
        while(sum--)
        {
            a=j;
            res.push_back(a);
            while(res.size()!=0)
            {
                check=true;
                a=res.back();
                vis1[a]=true;
                for(auto i:g[a])
                {
                    if(!vis[i])
                    {
                        int b=edges[i].first;
                        if(b==a)b=edges[i].second;
                        res.push_back(b);
                        vis[i]=true;
                        check=false;
                        a=b;
                        sum++;
                        break;
                     }
                }
                if(check||vis1[a])
                {
                    if(res.size()==1)break;
                    cout<<a<<" ";
                    res.pop_back();
                    while(res.back()!=a)
                    {
                        vis1[res.back()]=false;
                        cout<<res.back()<<" ";
                        res.pop_back();
                    }
                    cout<<endl;
                }
            }
            while(!res.empty())res.pop_back();
        }
    }
}
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