#include<bits/stdc++.h>
#define maxN 100005
using namespace std;
int niv[maxN],low[maxN];
bool seen[maxN];
stack<int> st;
vector<int> v[maxN];
int cbc,x;
vector<int> C[maxN];
inline void dfs(int nod,int tata,int Niv)
{
    seen[nod]=1;
    niv[nod]=Niv;
    low[nod]=Niv;
    st.push(nod);
    for(vector<int>::iterator it=v[nod].begin();it!=v[nod].end();it++)
    {
        if(*it==tata) continue;
        if(seen[*it])
        {
            low[nod]=min(low[nod],niv[*it]);
            continue;
        }
        dfs(*it,nod,Niv+1);
        low[nod]=min(low[nod],low[*it]);
        if(low[*it]>=niv[nod])
        {
            cbc++;
            do
            {
                x=st.top();
                st.pop();
                C[cbc].push_back(x);
            }while(x!=*it);
            C[cbc].push_back(nod);
        }
    }
}
int n,m,y;
int main()
{
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }

    dfs(1,0,1);

    printf("%d\n",cbc);
    for(int i=1;i<=cbc;i++)
    {
        sort(C[i].begin(),C[i].end());
        for(auto it:C[i])
        {
            printf("%d ",it);
        }
        printf("\n");
    }
    return 0;
}