#include <cstdio>
#include <vector>
 
using namespace std;

#define Nmax 221000
 
int n,m;
vector<int> G[Nmax];
vector<int> s[Nmax];
int viz[Nmax];
int sol;
int vf,nr;
int st[Nmax];
int low[Nmax];
int dfn[Nmax];
 
inline int min(int a, int b) { return a<b?a:b; }
 
void add(int x, int y)
{
    sol++;
    do
    {
        s[sol].push_back(st[--vf]);
        s[sol].push_back(st[--vf]);
    }
    while(st[vf+1]!=y || st[vf]!=x);
}
 
void dfs(int nod)
{
    viz[nod]=1;
 
    low[nod]=dfn[nod]=++nr;
 
    for (int i=0;i<G[nod].size();++i)
    {
        int x=G[nod][i];
        if (!viz[x])
        {
            st[vf++]=nod;
            st[vf++]=x;
            dfs(x);
            if (low[x]>=dfn[nod])
                add(nod,x);
            low[nod]=min(low[nod],low[x]);
        }
        else
            low[nod]=min(low[nod],dfn[x]);
    }
}
 
 
int main()
{
    int a,b,i,j;
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
 
    scanf("%d %d", &n, &m);
 
    for (i=1;i<=m;++i)
    {
        scanf("%d %d", &a, &b);
 
        G[a].push_back(b);
        G[b].push_back(a);
    }
 
    for (i=1;i<=n;++i)
         if (!viz[i])
             dfs(i);
 
    printf("%d\n", sol);
 
    for (i=1;i<=sol;++i)
    {
        for (j=0;j<s[i].size();++j)
        {
            int x=s[i][j];
            viz[x]=0;
        }
        for (j=0;j<s[i].size();++j)
             if (viz[s[i][j]]==0)
             {
                 viz[s[i][j]]=1;
                 printf("%d ", s[i][j]);
             }
        printf("\n");
    }

    return 0;
 
}