#include <bits/stdc++.h>
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int n,m,i,j,comp,k,x,y,L[1<<17],S[1<<17];
vector <int> V[1<<17],Sol[1<<17];
void dfs(int x,int y,int level)
{
    L[x]=level;
    S[++k]=x;
    for(int i=0;i<(int)V[x].size();++i)
    {
        if(!L[V[x][i]])
        {
            int ck=k;
            dfs(V[x][i],x,level+1);
            if(L[V[x][i]]>=level)
            {
                ++comp;
                while(k!=ck) Sol[comp].push_back(S[k--]);
                Sol[comp].push_back(x);
            }
        }
        if(V[x][i]!=y) L[x]=min(L[x],L[V[x][i]]);
    }
}
int main()
{
    f>>n>>m;
    while(m--)
    {
        f>>x>>y;
        V[x].push_back(y);
        V[y].push_back(x);
    }
    dfs(1,0,1);
    g<<comp<<'\n';
    for(i=1;i<=comp;++i,g<<'\n')
        for(j=0;j<(int)Sol[i].size();++j) g<<Sol[i][j]<<' ';
    return 0;
}