#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr int N=50005;
std::vector<int>g[N],vbcc[N];
int dfn[N],low[N],tot;
int stk[N],top;
int n,m,cnt;

void tarjan(int u,bool root){
    dfn[u]=low[u]=++tot;
    stk[++top]=u;
    if(root&&g[u].size()==0){
        return;
    }

    for(int v:g[u]){
        if(!dfn[v]){
            tarjan(v,false);
            low[u]=std::min(low[u],low[v]);
            if(low[v]>=dfn[u]){
                ++cnt;
                do{
                    vbcc[cnt].push_back(stk[top]);
                }while(stk[top--]!=v);
                vbcc[cnt].push_back(u);
            }
        }else{
            low[u]=std::min(low[u],dfn[v]);
        }
    }
}
bool cmp(std::vector<int>&a,std::vector<int>&b){
    int mn=std::min(a.size(),b.size());
    for(int i=0;i<mn;i++){
        if(a[i]==b[i])continue;
        return a[i]<b[i];
    }
    return a.size()<b.size();
}
void fc() {
    std::cin>>n>>m;
    for(int i=0;i<m;i++){
        int u,v;std::cin>>u>>v;
        if(u!=v){
            g[u].push_back(v);
            g[v].push_back(u);
        }
    }

    for(int i=1;i<=n;i++){
        if(!dfn[i])tarjan(i,false);
    }

    for(int i=1;i<=cnt;i++){
        std::sort(vbcc[i].begin(),vbcc[i].end());
    }
    std::sort(vbcc+1,vbcc+cnt+1,cmp);

    std::cout<<cnt<<"\n";
    for(int i=1;i<=cnt;i++){
        for(int v:vbcc[i])std::cout<<v<<" ";std::cout<<"\n";
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    //std::cin>>t;
    while (t--) fc();
    return 0;
}