#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

#define FIN "biconex.in"
#define FOUT "biconex.out"
#define MAX_N 100015
#define MAX_M 200015
#define PB push_back
#define MP make_pair

typedef pair<int, int> PII;

int N, M, S, C;
vector<int> G[MAX_N];
PII stack[MAX_M];
bool viz[MAX_N];
int lvl[MAX_N], mlvl[MAX_N], tata[MAX_N];
vector<int> comp[MAX_N];
int v[MAX_N];

void read() {
    scanf("%d %d", &N, &M);
    for (int i = 1; i <= M; ++i) {
        int a, b;
        scanf("%d %d", &a, &b);
        G[a].PB(b);
        G[b].PB(a);
    }
}

void DFS(int nod) {
    viz[nod] = true;
    mlvl[nod] = lvl[nod];

    for (vector<int>::iterator it = G[nod].begin(); it != G[nod].end(); ++it)
        if (*it != tata[nod])
            if (!viz[*it]) {
                lvl[*it] = lvl[nod] + 1;
                stack[++S] = MP(nod, *it);
                tata[*it] = nod;
                DFS(*it);
                if (mlvl[*it] >= lvl[nod]) {
                    ++C;
                    do {
                        if (v[stack[S].first] != C) {
                            comp[C].PB(stack[S].first);
                            v[stack[S].first] = C;
                        }
                        if (v[stack[S].second] != C) {
                            comp[C].PB(stack[S].second);
                            v[stack[S].second] = C;
                        }
                    } while (stack[S--] != MP(nod, *it));
                }
                mlvl[nod] = min(mlvl[nod], mlvl[*it]);
                
            } else {
                mlvl[nod] = min(mlvl[nod], lvl[*it]);
            }
}

void solve() {
    for (int i = 1; i <= N; ++i)
        if (!viz[i])
            DFS(i);
    printf("%d\n", C);
    for (int i = 1; i <= C; ++i) {
        for (int j = 0; j < (int)comp[i].size(); ++j)
            printf("%d ", comp[i][j]);
        printf("\n");
    }
}

int main() {
    freopen(FIN, "r", stdin);
    freopen(FOUT, "w", stdout);
    read();
    solve();
    return 0;
}