#include <bits/stdc++.h>
#define NMax 100001
using namespace std;

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

vector<int> G[NMax], c[NMax];
int n, m, x, y, low[NMax], level[NMax], comp;
bool viz[NMax];
stack<int> st;

void dfs(int nod, int parent)
{
    viz[nod] = true;
    level[nod] = level[parent] + 1;
    low[nod] = level[nod];
    st.push(nod);
    for(int i = 0; i < G[nod].size(); ++i)
        if(G[nod][i] != parent)
        {
            if(!viz[G[nod][i]])
            {
                dfs(G[nod][i], nod);
                low[nod] = min(low[nod], low[G[nod][i]]);
                if(low[G[nod][i]] >= level[nod])
                {
                    ++comp;
                    do
                    {
                        x = st.top();
                        c[comp].push_back(x);
                        st.pop();
                    }while(x != G[nod][i] && !st.empty());
                    c[comp].push_back(nod);
                }
            }
            else low[nod] = min(low[nod], level[G[nod][i]]);
        }
}

int main()
{
    f >> n >> m;
    while(f >> x >> y)
    {
        G[x].push_back(y);
        G[y].push_back(x);
    }

    for(int i = 1; i <= n; ++i)
        if(!viz[i]) dfs(i, 0);

    g << comp << '\n';

    for(int i = 1; i <= comp; ++i)
    {
        sort(c[i].begin(), c[i].end());
        for(int j = 0; j < c[i].size(); ++j)
            g << c[i][j] << " ";
        g << '\n';
    }

    return 0;
}