#include<fstream>
#include<vector>
#include<deque>
#define nx 100007
using namespace std;
int n,m,i,k,nr,x,y,viz[nx],low[nx],niv[nx];
vector<int>v[nx],sol[nx];
deque<int>q1,q2;

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

void adauga(int x)
{
    y=q1.back();
    k++;
    sol[k].push_back(x);
    if(x==y)
    {
        sol[k].push_back(q2.back());
        q1.pop_back(),q2.pop_back();
    }
    else
    while(x!=y && q1.size())
    {
        sol[k].push_back(q2.back());
        y=q1.back();
        q1.pop_back(),q2.pop_back();
    }
}

void dfs(int x)
{
    viz[x]=1;
    low[x]=niv[x];

    for(int j=0;j<v[x].size();j++)
    {
        int y=v[x][j];
        if(!viz[y])
        {
            niv[y]=niv[x]+1;
            if(x==i)nr++;

            q1.push_back(x);
            q2.push_back(y);

            dfs(y);

            if(low[y]<low[x])low[x]=low[y];
            if(low[y]>=niv[x] && x!=i)adauga(x);
        }
        low[x]=min(low[x],niv[y]);
    }

}

int main()
{
    fin>>n>>m;
    for(i=1;i<=m;i++)
    {
        fin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }

    for(i=1;i<=n;i++)
    if(!viz[i])
    {
        niv[i]=1;
        nr=0;
        dfs(i);
        if(nr>1)adauga(i);
    }

    k++;
    while(!q1.empty())sol[k].push_back(q1.front()),q1.pop_front();
    sol[k].push_back(q2.back());

    fout<<k<<'\n';
    for(i=1;i<=k;i++)
    {
        for(int j=0;j<sol[i].size();j++)fout<<sol[i][j]<<' ';
        fout<<'\n';
    }
    return 0;
}