#include <fstream>
#include <vector>
#include <list>
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int n,d[100001],low[100001],c=0;
vector <int> v[100001],sol[100001];
list < pair<int, int> > stiva;
void empty(int x,int y)
{
    while(stiva.front().first!=x && stiva.front().second!=y)
    {
        sol[c].push_back(stiva.front().second);
        stiva.pop_front();
    }
    sol[c].push_back(x);
    sol[c].push_back(y);
    stiva.pop_front();
}
void dfs(int x, int t)
{
    int i,y;
    d[x]=d[t]+1;
    low[x]=d[x];
    for(i=0;i<v[x].size();i++)
    {
        y=v[x][i];
        if(y!=t)
        {
            if(!d[y])
            {
                stiva.push_front(make_pair(x,y));
                dfs(y,x);
                if(low[y]<low[x]) low[x]=low[y];
                if(low[y]>=d[x]) {c++; empty(x,y);}
            }
            else if(d[y]<low[x]) low[x]=d[y];
        }
    }
}


int main()
{
    int i,j,m,x,y;
    f>>n>>m;

    for(i=1;i<=m;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    stiva.push_back(make_pair(1,0));
    dfs(1,0);
    g<<c<<'\n';
    for(i=1;i<=c;i++)
    {
        for(j=0;j<sol[i].size();j++)
            g<<sol[i][j]<<' ';
        g<<'\n';
    }
}