#include <bits/stdc++.h>

using namespace std;

ifstream fin("biconex.in");
ofstream fout("biconex.out");

int n, m, comp, timp;
vector<int>G[100001], Sol[100001];
int low[100001], disc[100001], TT[100001];
bool viz[100001];
stack<pair<int, int>>ST;

void DFS(int nod)
{
    int children=0;
    viz[nod]=1;
    low[nod]=disc[nod]=++timp;
    for(auto it:G[nod])
    {
        if(!viz[it])
        {
            ++children;
            ST.push(make_pair(nod, it));
            TT[it]=nod;
            DFS(it);
            low[nod]=min(low[nod], low[it]);
            if((TT[nod]==-1 && children>=2) || (TT[nod]!=-1 && low[it]>=disc[nod]))
            {
                int a, b;
                ++comp;
                do
                {
                    a=ST.top().first;
                    b=ST.top().second;
                    Sol[comp].push_back(b);
                    ST.pop();
                }while(a!=nod && b!=it);
                Sol[comp].push_back(a);
            }
        }
        else if(TT[nod]!=it) low[nod]=min(low[nod], disc[it]);
    }
}

int main()
{
    fin>>n>>m;
    for(int i=1; i<=m; ++i)
    {
        int x, y;
        fin>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    DFS(1);
    for(int i=1; i<=comp; ++i) sort(Sol[i].begin(), Sol[i].end());
    fout<<comp<<"\n";
    for(int i=1; i<=comp; ++i)
    {
        for(auto it:Sol[i]) fout<<it<<" ";
        fout<<"\n";
    }
    return 0;
}