#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],LL[1<<17];
vector <int> V[1<<17],Sol[1<<17];
void dfs(int x)
{
    S[++k]=x;
    for(auto it : V[x])
        if(!L[it])
        {
            int ck=k;
            L[it]=LL[it]=LL[x]+1;
            dfs(it);
            L[x]=min(L[x],L[it]);
            if(L[it]>=LL[x])
            {
                ++comp;
                while(k>ck) Sol[comp].push_back(S[k--]);
                Sol[comp].push_back(x);
            }
        }
        else L[x]=min(L[x],LL[it]);
}
int main()
{
    f>>n>>m;
    while(m--)
    {
        f>>x>>y;
        V[x].push_back(y);
        V[y].push_back(x);
    }
    L[1]=LL[1]=1;
    dfs(1);
    g<<comp<<'\n';
    for(i=1;i<=comp;++i,g<<'\n')
        for(auto it : Sol[i]) g<<it<<' ';
    return 0;
}