#include <bits/stdc++.h>

using namespace std;

ifstream f("biconex.in");
ofstream g("biconex.out");

int n,m,i,j,x,y,depth[100010],up[100010];
vector<vector<int> > C;
vector<int> c;
vector<int> v[100010];
bitset<100010> viz;
stack<int> St;

void dfs(int poz,int tata)
{
    viz[poz]=1;
    for(auto it:v[poz])
        if(it!=tata)
            if(!viz[it])
            {
                depth[it]=depth[poz]+1;
                up[it]=depth[it];
                St.push(it);
                dfs(it,poz);
                up[poz]=min(up[poz],up[it]);
                if(up[it]>=depth[poz])
                {
                    c.resize(0);
                    while(St.top()!=it)
                    {
                        c.push_back(St.top());
                        St.pop();
                    }
                    c.push_back(it);
                    c.push_back(poz);
                    St.pop();
                    C.push_back(c);
                }
            }
            else
                up[poz]=min(up[poz],depth[it]);
}

int main()
{
    f>>n>>m;
    for(i=1;i<=m;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for(i=1;i<=n;i++)
        if(!viz[i])
            dfs(i,0);
//    for(i=1;i<=n;i++)
//        g<<depth[i]<<' '<<up[i]<<'\n';
    g<<C.size()<<'\n';
    for(auto it:C)
    {
        for(auto that:it)
            g<<that<<' ';
        g<<'\n';
    }
    return 0;
}