#include<cstdio>
#include<vector>
using namespace std;
const int nmax = 100005;
int n,m,x,y,i,cnt,sol,dft[nmax],low[nmax];
vector<int> v[nmax],st,s[nmax];
void getsol(int x,int y)
{
    sol++;
    while(st.back()!=y)
    {
        s[sol].push_back(st.back());
        st.pop_back();
    }
    st.pop_back();
    s[sol].push_back(x);
    s[sol].push_back(y);
}
void dfs(int x,int f)
{
    dft[x]=low[x]=++cnt;
    for(vector<int>::iterator it=v[x].begin();it!=v[x].end();it++)
    {
        if(*it==f) continue;
        if(!dft[*it])
        {
            st.push_back(*it);
            dfs(*it,x);
            low[x]=min(low[x],low[*it]);
            if(low[*it]>=dft[x]) getsol(x,*it);
        }
        else low[x]=min(low[x],dft[*it]);
    }
}
int main()
{
	freopen("biconex.in","r",stdin);
	freopen("biconex.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(;m;m--)
	{
	    scanf("%d%d",&x,&y);
	    v[x].push_back(y);
	    v[y].push_back(x);
	}
	dfs(1,0);
	printf("%d\n",sol);
	for(i=1;i<=sol;i++,printf("\n"))
        for(vector<int>::iterator it=s[i].begin();it!=s[i].end();it++) printf("%d ",*it);
	return 0;
}