#include <iostream>
#include <fstream>
#include <stdio.h>
#include <queue>
#include <cstdlib>
#include <algorithm>
#include <iomanip>
#include <stack>

#if 1
#define pv(x) cout<<#x<<" = "<<x<<"; ";cout.flush()
#define pn cout<<endl
#else
#define pv(x)
#define pn
#endif

using namespace std;
ifstream in("biconex.in");
ofstream out("biconex.out");

#define ll long long
#define ull unsigned long long
#define pb push_back
#define mp make_pair
const int NMax = 1e5 + 5;
const int strMax = 1e7 + 5;

int N,M,nrComp;
int depth[NMax],lowPoint[NMax];
vector<int> v[NMax],comp[NMax];
stack< pair<int,int> > st;

void dfs(int,int);
void getComp(pair<int,int>);

int main() {
    in>>N>>M;

    for (int i=1;i <= M;++i) {
        int x,y;
        in>>x>>y;

        v[x].pb(y);
        v[y].pb(x);
    }

    dfs(1,0);

    out<<nrComp<<'\n';
    for (int i=1;i <= nrComp;++i) {
        for (int node : comp[i]) {
            out<<node<<' ';
        }
        out<<'\n';
    }

    /*
    for (int i=1;i <= N;++i) {
        pv(i);pv(depth[i]);pv(lowPoint[i]);pn;
    }
    //*/

    return 0;
}

void dfs(int node,int dad) {
    lowPoint[node] = depth[node] = depth[dad] + 1;
    st.push(mp(dad,node));

    for (int nxt : v[node]) {
        if (depth[nxt] != 0) {
            lowPoint[node] = min(lowPoint[node],depth[nxt]);
            continue;
        }

        dfs(nxt,node);
        lowPoint[node] = min(lowPoint[node],lowPoint[nxt]);

        if (lowPoint[nxt] == depth[node]) {
            ++nrComp;
            getComp(mp(node,nxt));
        }
    }
}

void getComp(pair<int,int> p) {
    while (st.top() != p) {
        comp[nrComp].pb( st.top().second );
        st.pop();
    }
    st.pop();

    comp[nrComp].pb( p.second );
    comp[nrComp].pb( p.first );
}