#include <bits/stdc++.h>

using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int n, m, x, y, dfn[100005], low[100005], nr;
bool viz[100005];
vector<int> graf[100005], rez[100005];
stack<int> s;

void Read()
{
  f>>n>>m;
  for(int i = 1;i <= m;++i)
    f>>x>>y, graf[x].push_back(y), graf[y].push_back(x);
}

void dfs(int nod, int parinte, int nivel)
{
  viz[nod] = true;
  dfn[nod] = low[nod] = nivel;
  s.push(nod);
  for(auto it : graf[nod])
    if(viz[it])
      low[nod] = min(low[nod], dfn[it]);
    else
    {
      dfs(it, nod, nivel + 1);
      low[nod] = min(low[nod], low[it]);
      if(low[it] >= dfn[nod])
      {
        ++nr;
        rez[nr].push_back(nod);
        do{
          x = s.top();
          s.pop();
          rez[nr].push_back(x);
        }while(x != it);
      }
    }
}

void Solve()
{
  dfs(1, -1, 1);
  g<<nr<<'\n';
  for(int i = 1;i <= nr;++i, g<<'\n')
    for(auto it : rez[i])
      g<<it<<" ";
}

int main()
{
  Read();
  Solve();
  return 0;
}