#include <iostream>
#include <cstdio>
#include <vector>
#include <stack>

#define NMAX 100001
#define MMAX 200001

using namespace std;

int n, m, x, y, k;
int niv[NMAX + 1];
int sus[NMAX + 1];
stack<pair<int, int> > R;
vector<int> G[MMAX];
vector<int> C[NMAX];

void dfs(int nod, int tata)
{
    niv[nod] = niv[tata] + 1;
    sus[nod] = niv[nod];
    for(int i = 1; i < G[nod].size(); i++)
        if(G[nod][i] != tata) {
            int nnod = G[nod][i];
            if(niv[nnod] != -1) {
                sus[nod] = min(sus[nod], sus[nnod]);
            } else {
                R.push(make_pair(nnod, nod));
                dfs(nnod, nod);
                sus[nod] = min(sus[nod], sus[nnod]);
                if(sus[nnod] >= niv[nod])
                {
                    while(!R.empty() && R.top().second != nod)
                    {
                        C[k].push_back(R.top().first);
                        R.pop();
                    }
                    C[k].push_back(R.top().first);
                    C[k].push_back(R.top().second);
                    R.pop();
                    k++;
                }
            }
        }
}

int main()
{
    freopen("biconex.in", "r", stdin);
    freopen("biconex.out", "w", stdout);
    scanf("%d %d", &n, &m);
    for(int i = 1; i <= n; i++)
        niv[i] = -1;
    for(int i = 1; i <= n; i++)
        G[i].push_back(0);
    for(int i = 1; i <= m; i++)
    {
        scanf("%d %d", &x, &y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
    for(int i = 1; i <= m; i++)
        if(niv[i] == -1)
        {
            dfs(i, 0);
        }
    printf("%d\n", k);
    for(int i = 0; i < k; i++)
    {
        for(int j = C[i].size() - 1; j >= 0 ; j--)
            printf("%d ", C[i][j]);
        printf("\n");
    }
    return 0;
}