#include <iostream>
#include <fstream>
#include <stack>
#include <vector>
#include <algorithm>
#define Nmax 100005
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
vector <int> Sol[Nmax],G[Nmax];
stack <int> S;
int N,M,level[Nmax],low[Nmax],use[Nmax],k;
void read()
{
    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);
    }
}
void sol(int x,int i)
{
    int nod=0;
    while(nod!=x)
    {
        nod=S.top();
        Sol[i].push_back(nod);
        S.pop();
    }
}
void DFS(int nod,int father)
{
    S.push(nod);
    use[nod]=1;
    level[nod]=level[father]+1;
    low[nod]=level[nod];
    for(int i=0;i<G[nod].size();i++)
    {
        int vecin=G[nod][i];
        if(vecin!=father)
        {
            if(!use[vecin])
            {
                S.push(nod);
                DFS(vecin,nod);
                low[nod]=min(low[nod],low[vecin]);
                if(low[vecin]>=level[nod])
                    sol(nod,++k);
            }
            else
                low[nod]=min(low[nod],level[vecin]);
        }
    }
}
void print()
{
    fout<<k<<"\n";
    for(int i=1;i<=k;i++)
    {
        sort(Sol[i].begin(),Sol[i].end());
        for(int j=0;j<Sol[i].size();j++)
            if(j==0 || Sol[i][j]!=Sol[i][j-1])
                fout<<Sol[i][j]<<" ";
        fout<<"\n";
    }
}
int main()
{
    read();
    DFS(1,0);
    print();
    return 0;
}