#include <bits/stdc++.h>
using namespace std;
int inf_int = 2e9;
long long inf_ll = 2e18;
const double pi = 3.1415926535898;
template <typename T, typename T1>
void prin(vector<pair<T, T1> >& a) {
  for (int i = 0; i < a.size(); i++) {
    cout << a[i].first << " " << a[i].second << "\n";
  }
}
template <typename T, typename T1>
void prin(set<pair<T, T1> >& a) {
  for (auto it = a.begin(); it != a.end(); it++) {
    cout << it->first << " " << it->second << "\n";
  }
}
template <typename T>
void prin(vector<T>& a) {
  for (int i = 0; i < a.size(); i++) {
    cout << a[i];
    if (i < a.size() - 1)
      cout << " ";
    else
      cout << "\n";
  }
}
template <typename T>
void prin(set<T>& a) {
  for (auto it = a.begin(); it != a.end(); it++) {
    cout << *it << " ";
  }
}
template <typename T>
void prin_new_line(vector<T>& a) {
  for (int i = 0; i < a.size(); i++) {
    cout << a[i] << "\n";
  }
}
template <typename T, typename T1>
void prin_new_line(vector<pair<T, T1> >& a) {
  for (int i = 0; i < a.size(); i++) {
    cout << a[i].first << " " << a[i].second << "\n";
  }
}
int sum_vec(vector<int>& a) {
  int s = 0;
  for (int i = 0; i < a.size(); i++) {
    s += a[i];
  }
  return s;
}
template <typename T>
T max(vector<T>& a) {
  T ans = a[0];
  for (int i = 1; i < a.size(); i++) {
    ans = max(ans, a[i]);
  }
  return ans;
}
template <typename T>
T min(vector<T>& a) {
  T ans = a[0];
  for (int i = 1; i < a.size(); i++) {
    ans = min(ans, a[i]);
  }
  return ans;
}
template <typename T>
T min(T a, T b, T c) {
  return min(a, min(b, c));
}
template <typename T>
T max(T a, T b, T c) {
  return max(a, max(b, c));
}
long double s_triangle(long double x1, long double y1, long double x2,
                       long double y2, long double x3, long double y3) {
  return abs(((x2 - x1) * (y3 - y1) - (x3 - x1) * (y2 - y1)) / 2);
}
bool overflow(long long a, long long b) {
  if (a * b / b != a) return true;
  return false;
}
bool debug = 0;
const int maxn = 5e5 + 100;
long long mod = 1e9 + 7;
vector<int> sor[maxn];
vector<int> g[maxn];
int ver[maxn];
int h;
char used[maxn];
vector<vector<int> > ans;
vector<int> com;
char bad[maxn];
void bfs(int v) {}
void solve() {
  int n, m;
  scanf("%d %d", &n, &m);
  for (int i = 0; i < m; i++) {
    int a, b;
    scanf("%d %d", &a, &b);
    sor[b].push_back(a);
    sor[a].push_back(b);
  }
  for (int i = 1; i <= n; i++) {
    for (int e = 0; e < sor[i].size(); e++) {
      g[sor[i][e]].push_back(i);
    }
  }
  for (int i = 1; i <= n; i++) {
    ver[i] = i;
  }
  h = n;
  for (int i = 1; i <= n; i++) {
    if (!used[i]) {
      com.clear();
      int v = i;
      used[v] = true;
      queue<int> q;
      q.push(v);
      while (!q.empty()) {
        int v = q.front();
        com.push_back(v);
        q.pop();
        for (int to : g[v]) {
          bad[to] = true;
        }
        for (int i = h; i >= 1; i--) {
          int to = ver[i];
          if (!used[to] && !bad[to]) {
            q.push(to);
            used[to] = true;
            swap(ver[i], ver[h]);
            h--;
          }
        }
        for (int to : g[v]) {
          bad[to] = false;
        }
      }
      ans.push_back(com);
    }
  }
  printf("%d\n", ans.size());
  for (int i = 0; i < ans.size(); i++) {
    printf("%d ", ans[i].size());
    for (int v : ans[i]) {
      printf("%d ", v);
    }
    printf("\n");
  }
}
int main() {
  if (!debug) {
  }
  int t = 1;
  while (t--) solve();
  return 0;
}
