#include <fstream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <stack>

using namespace std;

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

const int MAXN = 100005;
int n, m;
vector<int> v[MAXN];
bool viz[MAXN];
int l[MAXN], lm[MAXN];
int comp;
stack<int> s;
vector<int> sol[MAXN];

void biconex(int x, int y) {
    sol[comp].push_back(y);
    while (!s.empty() && s.top() != x) {
        sol[comp].push_back(s.top());
        s.pop();
    }
    if (!s.empty()) {
        sol[comp].push_back(x);
        s.pop();
    }
}

void dfs(int x, int p) {
    viz[x] = 1;
    l[x] = l[p] + 1;
    lm[x] = l[x];
    for (int i = 0; i < v[x].size(); ++i) {
        int node = v[x][i];
        if (node != p) {
            if (viz[node] == 1) {
                lm[x] = min(lm[x], l[node]);
            }
            else {
                s.push(node);
                dfs(node, x);
                lm[x] = min(lm[x], lm[node]);
                if (lm[node] >= l[x]) {
                    comp++;
                    biconex(node, x);
                }
            }
        }
    }
}



int main() {

    fin >> n >> m;
    for (int i = 1; i <= m; ++i) {
        int a, b;
        fin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }

    dfs(1, 0);

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

    fout.close();
    return 0;
}