#include <bits/stdc++.h>

using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
const int NMAX = 1e5;
vector <int> g[NMAX + 5];
int low[NMAX + 5], d[NMAX + 5];
bool vis[NMAX + 5];
int k = 0;
vector <int> bi[NMAX + 5];
stack <int> st;
void dfs(int u, int depth) {
    vis[u] = true;
    low[u] = d[u] = depth;
    st.push(u);
    for(int adj : g[u]) {
        if(vis[adj]) low[u] = min(low[u], d[adj]);
        else {
            dfs(adj, depth + 1);
            low[u] = min(low[u], low[adj]);
            if(low[adj] >= d[u]) {
                bi[++k] = {u};
                int x;
                do {
                    x = st.top();
                    st.pop();
                    bi[k].push_back(x);
                } while(x != adj);
            }
        }
    }
}

int main()
{
    int n, m, u, v;
    fin >> n >> m;
    for(int i = 1; i <= m; i++) {
        fin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs(1, 0);
    fout << k << "\n";
    for(int i = 1; i <= k; i++, fout << "\n")
        for(int x : bi[i])
            fout << x << " ";
    return 0;
}