#include <cstdio>
#include <vector>
#include <algorithm>
#define MaxN 100000
using namespace std;

vector<int> sol[2*MaxN+1];
vector<int> a[MaxN+1];
int deja[MaxN+1];
int viz[MaxN+1];
int stx[MaxN+1];
int sty[MaxN+1];
int h[MaxN+1];
int d[MaxN+1];
int N,M,K,T,vf;

void Add(int x, int y)
{
    ++K;
    while(stx[T] != x || sty[T] != y){
        if(viz[ stx[T] ] != K){
            sol[K].push_back(stx[T]);
            viz[ stx[T] ] = K;
        }
        if(viz[ sty[T] ] != K){
            sol[K].push_back(sty[T]);
            viz[ sty[T] ] = K;
        }

        --T;
    }

    if(viz[ stx[T] ] != K) sol[K].push_back(stx[T]);
    if(viz[ sty[T] ] != K) sol[K].push_back(sty[T]);
    --T;
}

void DFS(int x, int f)
{
    d[x] = h[x] = ++vf;
    deja[x] = 1;
    for(auto y : a[x])
    {
        if(y == f) continue;
        if(deja[y]) d[x] = min(d[x], h[y]);
        else {
            ++T;
            stx[T] = x; sty[T] = y;
            if(stx[T] > sty[T]) swap(stx[T], sty[T]);

            DFS(y, x);
            d[x] = min(d[x], d[y]);
            if(d[y] >= h[x]) Add(min(x,y), max(x,y));
        }
    }

    --vf;
}

int main(){
    FILE* fin = fopen("biconex.in","r");
    FILE* fout = fopen("biconex.out","w");

    int i,j,x,y;

    fscanf(fin,"%d %d",&N,&M);
    for(i = 1; i <= M; ++i)
    {
        fscanf(fin,"%d %d",&x,&y);
        a[x].push_back(y);
        a[y].push_back(x);
    }

    DFS(1, 0);
    fprintf(fout,"%d\n",K);
    for(i = 1; i <= K; ++i)
    {
        for(j = 0; j < sol[i].size(); ++j) fprintf(fout,"%d ",sol[i][j]);
        fprintf(fout,"\n");
    }


return 0;
}