#include <bits/stdc++.h>
#define dim int(1e5)+5
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int n,m,vf,comp;
bool seen[dim];
int low[dim],lvl[dim],st[dim];
vector <int> graph[dim],ans[dim];
void Read()
{
    f>>n>>m;
    for(int i=1;i<=m;++i)
    {
        int x,y;
        f>>x>>y;
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
}
void Dfs(int node,int daddy,int nivel)
{
    st[++vf]=node;
    low[node]=nivel;
    lvl[node]=nivel;
    seen[node]=1;
    for(int i=0;i<graph[node].size();++i)
    {
        int son=graph[node][i];
        if(son==daddy)continue;
        if(seen[son])
        {
            low[node]=min(low[node],lvl[son]);
            continue;
        }
        Dfs(son,node,nivel+1);
        low[node]=min(low[node],low[son]);
        if(low[son]>=lvl[node])
        {
            comp++;
            do
            {
                ans[comp].push_back(st[vf--]);
            }while(st[vf+1]!=son);
            ans[comp].push_back(node);
        }
    }
}
void Solve()
{
    Dfs(1,0,1);
    g<<comp<<'\n';
    for(int i=1;i<=comp;++i)
    {
        for(int j=0;j<ans[i].size();++j)
            g<<ans[i][j]<<" ";
        g<<'\n';
    }
}
int main()
{
    Read();
    Solve();
    return 0;
}