#include <climits>
#include <cstdio>
#include <cstring>
#include <set>
#include <stack>

#define NMAX 100000
#define MMAX 200000

static struct edge {
    int n, v, bcc;
} edges[2*MMAX+1];

static struct pair {
    int u, v;
} bridges[2*MMAX+1];

static enum c {
    WHITE,
    GRAY,
    BLACK
} color[NMAX];

inline static int min(int a, int b)
{
    return a < b ? a : b;
}

static int adj[NMAX], low[NMAX], is_art[NMAX], d[NMAX], parent[NMAX], dc, nbridges, nbcc;
static std::set<int> bcc[NMAX];
static std::stack<struct pair> edge_stack;

static void dfs(int s)
{
    int e, nchld = 0;

    low[s] = d[s] = ++dc;
    color[s] = GRAY;

    for (e = adj[s]; e != 0; e = edges[e].n) {
        if (parent[s] != edges[e].v && color[edges[e].v] == GRAY) {
            low[s] = min(low[s], low[edges[e].v]);
        } else if (color[edges[e].v] == WHITE) {
            nchld++;

            parent[edges[e].v] = s;
            edge_stack.push({s, edges[e].v});
            dfs(edges[e].v);
            low[s] = min(low[s], low[edges[e].v]);

            if (low[edges[e].v] >= d[s]) {
                is_art[s] = s != 1 || nchld > 1;
                if (is_art[s]) {
                    while (edge_stack.top().u != s || edge_stack.top().v != edges[e].v) {
                        bcc[nbcc].insert(edge_stack.top().u);
                        bcc[nbcc].insert(edge_stack.top().v);
                        edge_stack.pop();
                    }
                    bcc[nbcc].insert(edge_stack.top().u);
                    bcc[nbcc].insert(edge_stack.top().v);
                    edge_stack.pop();
                    nbcc++;
                }
            }

            if (low[edges[e].v] > d[s]) {
                bridges[nbridges].u = s;
                bridges[nbridges].v = edges[e].v;
                nbridges++;
            }
        }
    }

    color[s] = BLACK;
}

static void find_art(int n)
{
    int i;

    for (i = 1; i <= n; i++) {
        low[i] = INT_MAX;
    }

    dfs(1);

    i = 0;
    while (!edge_stack.empty()) {
        i = 1;
        bcc[nbcc].insert(edge_stack.top().u);
        bcc[nbcc].insert(edge_stack.top().v);
        edge_stack.pop();
    }

    if (i) {
        nbcc++;
    }
}

int main(void)
{
    int n, m, i, u, v;

    scanf("%d %d", &n, &m);

    for (i = 1; i <= m; i++) {
        scanf("%d %d", &u, &v);

        edges[2*i].v = u;
        edges[2*i].n = adj[v];
        adj[v] = 2*i;

        edges[2*i+1].v = v;
        edges[2*i+1].n = adj[u];
        adj[u] = 2*i+1;
    }

    find_art(n);

    //for (i = 1; i <= n; i++) {
        //printf("%d: d=%d low=%d\n", i, d[i], low[i]);
    //}

    //for (i = 1; i <= n; i++) {
        //if (is_art[i]) {
            //printf("%d ", i);
        //}
    //}
    //printf("\n");

    //for (i = 0; i < nbridges; i++) {
        //printf("(%d, %d)%c", bridges[i].u, bridges[i].v, " \n"[i == nbridges - 1]);
    //}

    printf("%d\n", nbcc);
    for (i = 0; i < nbcc; i++) {
        for (auto it : bcc[i]) {
            printf("%d ", it);
        }
        printf("\n");
    }

    return 0;
}