#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#define inf 0x3f3f3f
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int n,m,st[100005],niv[100005],use[100005],num,k,dad[100005],mniv[100005];
vector<int> v[100005],b[100005];

void DFS(int x)
{ int i,lim;
   use[x]=1; num++; st[num]=x;

  for(i=0;i<v[x].size();i++)
   if (!use[v[x][i]])
   { niv[v[x][i]]=niv[x]+1;

     lim=num;
     DFS(v[x][i]);
     mniv[x]=min(mniv[x],mniv[v[x][i]]);
     if (mniv[v[x][i]]>=niv[x])
     { k++;
      if (x==2) cout<<mniv[3];
        while(num>lim)
        { b[k].push_back(st[num]);
          num--;
        }
       b[k].push_back(x);
     }
   }
   else
    mniv[x]=min(mniv[x],niv[v[x][i]]);
}

int main()
{ int i,j,x,y;

    f>>n>>m;
    memset(mniv,inf,sizeof(mniv));
    for(i=1;i<=m;i++)
    { f>>x>>y;
      v[x].push_back(y);
      v[y].push_back(x);
    }
   niv[1]=1;
   DFS(1);
 //cout<<mniv[2];
    g<<k<<"\n";
   for(i=1;i<=k;i++)
   {
      for(j=0;j<b[i].size();j++)
       g<<b[i][j]<<" ";

     g<<"\n";
   }
    return 0;
}