#include <fstream>
#include <vector>

using namespace std;

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

const int nmax = 100005;
int stiva[nmax], vf, nc;
bool viz[nmax];
int niv[nmax], lmax[nmax], n, i, j, x, y, m;
vector <int> ls[nmax], sol[nmax];

void pune(int x, int tt) {
    int c;
    sol[nc].push_back(tt);
    while (vf > 0 && (c=stiva[vf]) != x) {
        sol[nc].push_back(c);
        vf--;
    }
    if (vf) {
        sol[nc].push_back(x);
        vf--;
    }
}

void dfs(int x, int tt) {
    int l = ls[x].size(), i, y;
    viz[x] = 1;
    lmax[x] = niv[x] = niv[tt] + 1;
    for (i = 0; i < l; i++) {
        y = ls[x][i];
        if (y == tt) continue;
        if (viz[y] == 1) {
            lmax[x] = min(lmax[x],niv[y]);
            continue;
        }
        stiva[++vf] = y;
        dfs(y,x);
        lmax[x] = min(lmax[x], lmax[y]);
        if (niv[x] <= lmax[y]) {
            nc++;
            pune(y, x);
        }
    }

}

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

    dfs(1,0);

    g << nc << '\n';
    for (i = 1; i <= nc; i++) {
        for (j = 0; j < sol[i].size(); j++)
            g << sol[i][j] << ' ';
        g << '\n';
    }
}