#include <stdio.h>
#include <vector>
#include <algorithm>
#define maxn 100010
using namespace std;
int low[maxn],ind[maxn],t[maxn],stack[2*maxn],i,j,n,m,timp,bcc,top;
vector<int> comp[maxn],g[maxn];
char s[maxn];
void add(int v,int w)
{
    int i,j; vector<int> aux;
    bcc++;
    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[bcc].push_back(aux[0]);
    for(i=1; i<aux.size(); i++)
     if(aux[i]!=aux[i-1])
      comp[bcc].push_back(aux[i]);
}
void dfs(int v)
{
    int i; s[v]=1;
    low[v]=ind[v]=++timp;
    for(i=0; i<g[v].size(); ++i)
     if(!s[g[v][i]])
     {
         t[g[v][i]]=v;
         stack[++top]=v;
         stack[++top]=g[v][i];
         dfs(g[v][i]);
         if(low[g[v][i]]>=ind[v]) add(v,g[v][i]);
         low[v]=min(low[v],low[g[v][i]]);
     }
     else
      if(g[v][i]!=t[v])
       low[v]=min(low[v],ind[g[v][i]]);
}
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++)
    {
        timp=0;
        dfs(i);
    }
    printf("%d\n",bcc);
    for(i=1; i<=bcc; i++)
    {
        for(j=0; j<comp[i].size(); ++j)
         printf("%d ",comp[i][j]);
        printf("\n");
    }
    return 0;
}