#include<bits/stdc++.h>
using namespace std;

const int maxN=100005;
int st[maxN],vf,low[maxN],biconexe,niv[maxN];
bool seen[maxN];
vector<int> v[maxN],C[maxN];

void dfs(int nod,int fat,int lvl)
{
    st[++vf]=nod;
    low[nod]=niv[nod]=lvl;
    seen[nod]=1;


    for(auto it:v[nod])
    {
        if(it==fat) continue;

        if(seen[it])
        {
            low[nod]=min(low[nod],niv[it]);
            continue;
        }

        dfs(it,nod,lvl+1);

        low[nod]=min(low[nod],low[it]);

        if(low[it]>=niv[nod])
        {
            biconexe++;
            int x=0;
            do
            {
                x=st[vf];
                C[biconexe].push_back(x);
                vf--;
            }while(x!=it);

            C[biconexe].push_back(nod);
        }
    }
}
int n,m,x,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",biconexe);

    for(int i=1;i<=biconexe;i++)
    {
        for(auto it:C[i])
            printf("%d ",it);

        printf("\n");
    }

    return 0;
}