#include <fstream>
#include <bits/stdc++.h>

using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
int n, m, i, j, x, y, depth[100005], nma[100005], nr;
vector <int> v[100005], biconex[100005];
bool viz[100005];
stack <int> st;
void dfs(int nod, int par)
{
    viz[nod]=1;
    st.push(nod);
    depth[nod]=depth[par]+1;
    nma[nod]=depth[nod];
    for(auto i: v[nod])
        if(i!=par)
    {
        if(viz[i])
            nma[nod]=min(nma[nod], depth[i]);
        else
        {
            dfs(i, nod);
            nma[nod]=min(nma[nod], nma[i]);
            if(depth[nod]<=nma[i])
            {
                nr++;
                do
                {
                    x=st.top();
                    st.pop();
                    biconex[nr].push_back(x);
                }while(x!=i);
                biconex[nr].push_back(nod);
            }
        }
    }
}
int main()
{
    fin>>n>>m;
    for(i=1; i<=m; i++)
    {
        fin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    dfs(1, -1);
    for(i=1; i<=nr; i++)
    {
        for(auto j: biconex[i])
          fout<<j<<" ";
        fout<<'\n';
    }

    return 0;
}