#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
#define DIM 100010

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

vector<int> L[DIM];
vector<int> R[DIM];
stack< pair<int, int> > s;
int v[DIM], low[DIM];

pair<int, int> p;
int n, m, i, j, x, y, cbc;

void dfs(int nod, int tata, int niv) {
    v[nod] = niv;
    low[nod] = niv;
    for (int i = 0;i<L[nod].size(); i++) {
        if (L[nod][i] == tata)
            continue;
        if (v[ L[nod][i] ] == 0) {
            s.push(make_pair(nod, L[nod][i]));
            dfs(L[nod][i], nod, niv+1);
            low[nod] = min(low[nod], low[ L[nod][i] ]);

            if (low[ L[nod][i] ] >= niv) {
                cbc++;
                do {
                    p = s.top();
                    s.pop();
                    R[cbc].push_back(p.first);
                    R[cbc].push_back(p.second);
                } while (nod!=p.first || L[nod][i]!=p.second);
            }
        } else
            low[nod] = min(low[nod], low[ L[nod][i] ]);

    }
}

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

    for (i=1;i<=n;i++)
        if (v[i] == 0)
            dfs(i, 0, 1);
    fout<<cbc<<"\n";

    for (i=1;i<=cbc;i++) {
        sort(R[i].begin(), R[i].end());
        fout<<R[i][0]<<" ";
        for (j=1;j<R[i].size(); j++)
            if (R[i][j] != R[i][j-1])
                fout<<R[i][j]<<" ";
        fout<<"\n";
    }

    return 0;
}