#include<bits/stdc++.h>
using namespace std;
const int N=2e5+10;
int n,m;
#define pi pair<int,int>
#define pb push_back
#define fi first
#define se second
vector<pi>g[N];
int fp[N],fa[N],d[N];
bool sb[N];
void dfs(int x){
    for(pi t:g[x]){
        int v=t.fi,w=t.se;
        if(!fp[v])fp[v]=x,sb[w]=1,d[v]=d[x]+1,dfs(v);
    }
}
int F(int x){
    if(x==fa[x])return x;
    return fa[x]=F(fa[x]);
}
int U[N],V[N];
vector<int>E[N];
int main(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)fa[i]=i;
    for(int i=1,u,v;i<=m;i++){
        scanf("%d%d",&u,&v),u++,v++;
        U[i]=u,V[i]=v;
        g[u].pb({v,i}),g[v].pb({u,i});
    }
    for(int i=1;i<=n;i++)if(!fp[i])fp[i]=i,dfs(i);
    for(int i=1;i<=m;i++)if(!sb[i]){
        int u=F(U[i]),v=F(V[i]);if(d[u]<d[v])swap(u,v);
        while(u!=v)
            fa[u]=F(fp[u]),u=fa[u];
    }
    int e=0;
    for(int i=1;i<=n;i++){
        E[F(i)].pb(i);
        if(fa[i]==i)e++;
    }
    printf("%d\n",e);
    for(int i=1;i<=n;i++)if(F(i)==i){
        printf("%d ",E[i].size());for(int x:E[i])printf("%d ",x-1);
        puts("");
    }
    return 0;
}