#include <fstream>
#include <iostream>
#include <set>
#include <stack>
#include <vector>
#include <algorithm>
using namespace std;
const char iname[] = "biconex.in";
const char oname[] = "biconex.out";
#define MAXN 100005
#define Min(a, b) ((a) < (b) ? (a) : (b))
vector <int> adj[MAXN], dfn, low;
vector <vector <int> > C;
stack <pair <int, int> > stk;
void read_in(vector <int>* adj, int &n)
{
ifstream in(iname);
int cnt_edges, x, y;
in >> n >> cnt_edges;
for (; cnt_edges > 0; -- cnt_edges) {
in >> x >> y;
adj[x].push_back(y);
adj[y].push_back(x);
}
in.close();
}
void cache_bc(const int x, const int y)
{
vector <int> con; int tx, ty;
do {
tx = stk.top().first, ty = stk.top().second;
stk.pop();
con.push_back(tx), con.push_back(ty);
}
while (tx != x || ty != y);
C.push_back(con);
}
void DF(const int n, const int fn, int number)
{
vector <int>::iterator it;
dfn[n] = low[n] = number;
for (it = adj[n].begin(); it != adj[n].end(); ++ it) {
if (*it == fn) continue ;
if (dfn[*it] == -1) {
stk.push( make_pair(n, *it) );
DF(*it, n, number + 1);
low[n] = Min(low[n], low[*it]);
if (low[*it] >= dfn[n])
cache_bc(n, *it);
}
else
low[n] = Min(low[n], dfn[*it]);
}
}
/* GENERATOR */
set <pair <int, int> > S;
vector <pair <int, int> > V;
vector <int> G[MAXN], used, STK;
void BuildATree(int n, const int diff)
{
for (STK.push_back(n); STK.size(); ) {
n = STK.back();
if (used[n] == 0) {
used[n] = 1;
if (STK.size() % diff == 0)
S.insert( make_pair(n, STK[STK.size() - diff + (rand() % 4)]) );
}
int cnt = 0;
for (int i = 0; i < G[n].size(); ++ i)
cnt += (used[ G[n][i] ] == 0);
if (cnt == 0) { // are descendenti?
STK.pop_back();
continue ;
}
cnt = (rand() % cnt) + 1;
int m;
for (int i = 0; i < G[n].size(); ++ i)
if ((cnt -= (used[ G[n][i] ] == 0)) == 0) {
m = G[n][i];
break ;
}
S.insert( make_pair(n, m) );
STK.push_back(m);
}
}
void generate(const int n, const int eps, const int diff)
{
ofstream out(iname);
srand(unsigned(time(NULL)));
S.clear();
for (int i = 1; i <= n; ++ i)
vector <int>().swap(G[i]);
for (int i = 1; i < n; ++ i) {
S.insert( make_pair(i, i + 1) );
G[i].push_back(i + 1), G[i + 1].push_back(i);
}
for (int i = 1; i <= eps; ++ i) {
int x = (rand() % n) + 1, y = (rand() % n) + 1;
if (x == y)
continue ;
if (x > y)
swap(x, y);
if (S.find( make_pair(x, y) ) != S.end())
continue ;
S.insert( make_pair(x, y) );
G[x].push_back(y), G[y].push_back(x);
}
used.resize(n + 1), used.assign(used.size(), 0);
S.clear();
BuildATree(1, diff);
while (S.size()) {
V.push_back(*S.begin());
S.erase(S.begin());
}
random_shuffle(V.begin(), V.end());
// Scriere in fisier
out << n << " " << V.size() << "\n";
for (int i = 0; i < V.size(); ++ i)
out << V[i].first << " " << V[i].second << "\n";
out.close();
}
/* MAIN */
int main(void)
{
// generate(100000, 100000, 64); return 0;
int n;
read_in(adj, n);
dfn.resize(n + 1), dfn.assign(n + 1, -1);
low.resize(n + 1);
DF(1, 0, 0);
ofstream out(oname);
out << C.size() << "\n";
for (int i = 0; i < C.size(); ++ i) {
sort(C[i].begin(), C[i].end());
C[i].erase(unique(C[i].begin(), C[i].end()), C[i].end());
out << "* ";
for (int j = 0; j < C[i].size(); ++ j)
out << C[i][j] << " ";
out << "\n";
}
out.close();
return 0;
}