/*
 Catalin-Stefan Tiseanu
 Pre-written code is assembled from various sources found online.
 Big thanks to the community for that !
 */
// Pre-written code below

using namespace std;

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#include <unordered_map>
#include <unordered_set>

//START_CLEAN
// always remove

//START:mandatory
//#define DEBUG

#ifndef NDEBUG
#   define assert_msg(condition, message) \
do { \
if (! (condition)) { \
std::cerr << "Assertion `" #condition "` failed in " << __FILE__ \
<< " line " << __LINE__ << ": " << message << std::endl; \
std::exit(EXIT_FAILURE); \
} \
} while (false)
#else
#   define ASSERT(condition, message) do { } while (false)
#endif

#ifdef DEBUG
#define debug(args...)            {dbg,args; cerr<<endl;}
#else
#define debug(args...)              // Just strip off all debug tokens
#endif

template<class T> std::ostream&  operator <<(std::ostream& stream, const vector<T> & v) {
  for (auto el : v)
    stream << el << " ";
  return stream;
}

template<class T> std::ostream&  operator <<(std::ostream& stream, const vector<vector<T>> & v) {
  for (auto line : v) {
    for (auto el : line)
      stream << el << " ";
    stream << endl;
  }
  return stream;
}

template<class T, class U> std::ostream&  operator <<(std::ostream& stream, const pair<U, T> & p) {
  stream << "( " << p.first << ", " << p.second << " )";
  return stream;
}

class debugger {
public:
  template<class T> void output (const T& v) {
    cerr << v << " ";
  }
  
  template<class T> debugger& operator , (const T& v) {
    output(v);
    return *this;
  }
} dbg;
//END:mandatory

////////////////
// templates  //
////////////////

// general
//template size
template<typename T> int size(const T& c) { return int(c.size()); }
//template abs
template<typename T> T abs(T x) { return x < 0 ? -x : x; }
//template sqr
template<typename T> T sqr(T x) { return x*x; }
//template remin
template<typename T> bool remin(T& x, T y) { if (x <= y) return false; x = y; return true; }
//template remax
template<typename T> bool remax(T& x, T y) { if (x >= y) return false; x = y; return true; }
//template factorize
template<class T> inline vector<pair<T,int> > factorize(T n) {vector<pair<T,int> > R;for (T i=2;n>1;){if (n%i==0){int C=0;for (;n%i==0;C++,n/=i);R.push_back(make_pair(i,C));} i++;if (i>n/i) i=n;}if (n>1) R.push_back(make_pair(n,1));return R;}
//template toStr
template<typename T> string toStr(T x) { stringstream ss; ss << x; return ss.str(); }

// other
string maskToStr(long long x, int len) {stringstream ss; for (int i = 0; i < len; ++i) if (x >> i & 1) ss << "1"; else ss << "0"; return ss.str();}

// misc
#define EPS             1e-5

// types
//template int64
typedef long long            int64 ;
//template uint64
typedef unsigned long long   uint64 ;

// shortcuts
#define all(_xx)             _xx.begin(), _xx.end()

#define pb                   push_back
#define vi                   vector<int>
#define vs                   vector<string>
#define vvi                  vector<vector<int>>
#define vd                   vector<double>
#define vpii                 vector<pair<int,int> >
#define vpdd                 vector<pair<double,double> >

#define pii                  pair<int,int>
#define pll                  pair<long long, long long>
#define pdd                  pair<double, double>
#define mp(XX, YY)           make_pair(XX, YY)
#define fi                   first
#define se                   second

#define ll                   long long
#define SS                   stringstream

// for loops
#define re(II, NN)           for (int II(0), _NN(NN); (II) < (NN); ++(II))
#define fod(II, XX, YY)      for (int II(XX), _YY(YY); (II) >= (_YY); --(II))
#define fo(II, XX, YY)       for (int II(XX), _YY(YY); (II) <= (_YY); ++(II))
#define foreach(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();++it)

// Useful hardware instructions
#define bitcount             __builtin_popcount
#define gcd                  __gcd

// Useful all around
#define checkbit(n,b)        ( (n >> b) & 1)
#define DREP(a)              sort(a.begin(), a.end());a.erase(unique(a.begin(), a.end()),a.end())
#define INDEX(arr,ind)       (lower_bound(arr.begin(), arr.end(),ind)-arr.begin())
#define PAUSE cerr << "Press any key to continue ..."; char xxxx; scanf("%c", &xxxx);
#define fill(xx,val) memset(xx, val, sizeof(xx))

struct Scanner {
  char* curPos;
  
  const static int BUF_SIZE = (2000000);
  char input[BUF_SIZE];
  
  FILE * fin;
  
  void init(FILE * _fin) {
    fin = _fin;
    fread(input, 1, sizeof(input), fin);
    curPos = input;
  }
  
  Scanner() {;}
  
  inline void ensureCapacity() {
    int size = input + BUF_SIZE - curPos;
    if (size < 100) {
      memcpy(input, curPos, size);
      fread(input + size, 1, BUF_SIZE - size, fin);
      curPos = input;
    }
  }
  
  inline int nextInt() {
    ensureCapacity();
    while (!isdigit(*curPos) && *curPos != '-')
      ++curPos;
    int res = 0;
    int sign = 1;
    
    if (*curPos == '-')
      sign = -1,
      ++curPos;
    
    while (*curPos >= '0' && *curPos <= '9')
      res = res * 10 + (*(curPos++) & 15);
    return sign * res;
  }
} Sc;

// code starts here
struct BiconnectedGraph {
  // doit by edges
  // result[i] = biconnected component of node i (by edges)
  int N;
  vvi g;
  vi depth, parent, low;
  vector<bool> visited;
  vi comp_edge;
  vvi comp_vertex;
  
  struct UnionFind {
    vector<int> p;
    
    int gp(int x) {
      if (p[x] != x) {
        p[x] = gp(p[x]);
      }
      return p[x];
    }
    
    void un(int a, int b) {
      p[gp(a)] = gp(b);
    }
    
    void init(int n) {
      p.reserve(n);
      re (i, n) p.pb(i);
    }
    
    UnionFind() {;}
    UnionFind(int n) {init(n);}
  } uf;
  
  void dfs_low(int x) {
    visited[x] = true;
    low[x] = depth[x];
    for (auto it : g[x]) {
      if (!visited[it]) {
        depth[it] = depth[x] + 1;
        parent[it] = x;
        dfs_low(it);
        low[x] = min(low[x], low[it]);
        if (low[it] <= depth[x]) {
          uf.un(x, it);
        }
      } else if (it != parent[x]) {
        low[x] = min(low[x], depth[it]);
      }
    }
  }
  
  void getByEdges() {
    N = g.size();
    uf.init(N);
    
    visited = vector<bool>(N, false);
    parent = vi(N, -1);
    depth = vi(N, 0);
    low = vi(N, -1);
    
    visited.reserve(N);
    parent.reserve(N);
    depth.reserve(N);
    low.reserve(N);
    
    re (i, N)
    if (!visited[i])
      dfs_low(i);
    
    comp_edge.clear();
    comp_edge.reserve(N);
    
    re (i, N) comp_edge.pb(uf.gp(i));
  }
  
  void add_to_comp(int x, vi & comp) {
    if (visited[x]) return;
    visited[x] = true;
    comp.pb(x);
    for (auto y : g[x])
      if (!visited[y] && comp_edge[x] == comp_edge[y])
        add_to_comp(y, comp);
  }
  
  void getByVertices() {
    getByEdges();
    
    re (i, N) visited[i] = false;
    comp_vertex.reserve(N);
    
    re (x, N)
    for (auto y : g[x]) {
      debug(x, y, comp_edge[x], comp_edge[y]);
      if (comp_edge[x] != comp_edge[y] && x < y) {
        vi cur_comp(2);
        cur_comp[0] = x, cur_comp[1] = y;
        comp_vertex.pb(cur_comp);
      } else if (!visited[x]) {
        comp_vertex.pb(vi());
        add_to_comp(x, comp_vertex.back());
        if (comp_vertex.back().size() == 1)
          comp_vertex.pop_back();
      }
    }
  }
  
  void init(int N) {
    g.clear();
    g.resize(N);
    g.reserve(N);
  }
  
  inline void add_edge(int x, int y) {
    g[x].pb(y);
  }
} G;

int main() {
  freopen("biconex.in", "r", stdin);
  freopen("biconex.out", "w", stdout);
  
  int N, M;
  
  Sc.init(stdin);
  N = Sc.nextInt(), M = Sc.nextInt();
  
  G.init(N);
  
  fo (i, 1, M) {
    int x = Sc.nextInt(), y = Sc.nextInt();
    --x, --y;
    G.add_edge(x, y);
    G.add_edge(y, x);
  }
  
  G.getByVertices();
  printf("%d\n", G.comp_vertex.size());
  re (i, G.comp_vertex.size()) {
    printf("%d", G.comp_vertex[i][0] + 1);
    fo (j, 1, G.comp_vertex[i].size() - 1)
      printf(" %d", G.comp_vertex[i][j] + 1);
    printf("\n");
  }
  
  return 0;
}