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

using namespace std;

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

int n, m, cnt = 0, niv = 0, T[100001], Niv[100001], NivMin[100001];
vector<int> G[100001];
vector<int> Cb[100001];
stack<pair<int, int>> Stack;
bool V[100001];

void Dfs(int x)
{
    V[x] = true;
    ++niv;
    Niv[x] = NivMin[x] = niv;
    for (int y : G[x])
    {
        if (!V[y])
        {
            T[y] = x;
            Stack.emplace(x, y);
            Dfs(y);
            NivMin[x] = min(NivMin[x], NivMin[y]);
            if (NivMin[y] >= Niv[x])
            {
                ++cnt;
                while (true)
                {
                    int i = Stack.top().first, j = Stack.top().second;
                    Stack.pop();
                    Cb[cnt].push_back(i);
                    Cb[cnt].push_back(j);
                    if (i == x)
                        break;
                }
            }
        }
        else if (y != T[x])
            NivMin[x] = min(NivMin[x], Niv[y]);
    }
}

int main()
{
    fin >> n >> m;
    for (int i = 1; i <= m; ++i)
    {
        int x, y;
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    for (int i = 1; i <= n; ++i)
    {
        if (!V[i])
            Dfs(i);
    }
    fout << cnt << '\n';
    for (int i = 1; i <= cnt; ++i)
    {
        sort(Cb[i].begin(), Cb[i].end());
        for (int j = 0; j < Cb[i].size(); ++j)
        {
            if (j == 0 || Cb[i][j - 1] != Cb[i][j])
                fout << Cb[i][j] << " ";
        }
        fout << '\n';
    }

    return 0;
}