#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define N 100001
int n,m,i,o,k,x,y,l[N],s[N],c[N];
vector<int> v[N],t[N];
void D(int x)
{
    int z;
    s[++k]=x;
    for(auto i:v[x])
        if(!l[i])
        {
            z=k,l[i]=c[i]=c[x]+1,D(i),l[x]=min(l[x],l[i]);
            if(l[i]>=c[x])
            {
                for(o++;k>z;t[o].pb(s[k--]));
                t[o].pb(x);
            }
        }
        else
            l[x]=min(l[x],c[i]);
}
int main()
{
    freopen("biconex.in","r",stdin),freopen("biconex.out","w",stdout),scanf("%d%d",&n,&m);
    while(m--)
        scanf("%d%d",&x,&y),v[x].pb(y),v[y].pb(x);
    l[1]=c[1]=1,D(1),printf("%d\n",o);
    for(i=1;i<=o;i++,printf("\n"))
        for(auto j:t[i])
            printf("%d ",j);
}