#include <stdio.h>
#include <vector>
#include <algorithm>
#define max 100010
using namespace std;
vector<int> g[max],comp[max];
typedef vector<int>::iterator IT;
int n,m,i,j,timp,low[max],ind[max],t[max],stack[max],top,scc;
char s[max];
void add(int v,int w)
{
    scc++;
    int i,j;
    vector<int> aux;
    do
    {
        j=stack[top--]; i=stack[top--];
        aux.push_back(i);
        aux.push_back(j);
    }
    while(i!=v || j!=w);

    sort(aux.begin(),aux.end());
    comp[scc].push_back(aux[0]);
    for(int i=1; i<aux.size(); i++)
     if(aux[i]!=aux[i-1])
      comp[scc].push_back(aux[i]);
}

void dfs(int v)
{
    s[v]=1;
    low[v]=ind[v]=++timp;
    for(IT i=g[v].begin(); i!=g[v].end(); ++i)
     if(!s[*i])
     {
         t[*i]=v;
         stack[++top]=v;
         stack[++top]=*i;
         dfs(*i);
         low[v]=(low[v]>low[*i]) ? low[*i]:low[v];
         if(low[*i]>=ind[v]) add(v,*i);
     }
     else
      if(*i!=t[v])
       low[v]=(low[v]>ind[*i]) ? ind[*i]:low[v];
}
int main()
{
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(; m--; )
    {
        scanf("%d%d",&i,&j);
        g[i].push_back(j);
        g[j].push_back(i);
    }
    for(i=1; i<=n; i++)
     if(!s[i])
     {
         timp=0;
         dfs(i);
     }
    printf("%d\n",scc);
    for(i=1; i<=scc; i++)
    {
        for(IT j=comp[i].begin(); j!=comp[i].end(); ++j)
         printf("%d ",*j);
        printf("\n");
    }
    return 0;
}