#include <bits/stdc++.h>
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")
using namespace std;
template <class T>
inline T bigmod(T p, T e, T M) {
  long long ret = 1;
  for (; e > 0; e >>= 1) {
    if (e & 1) ret = (ret * p) % M;
    p = (p * p) % M;
  }
  return (T)ret;
}
template <class T>
inline T gcd(T a, T b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
template <class T>
inline T modinverse(T a, T M) {
  return bigmod(a, M - 2, M);
}
template <class T>
inline T lcm(T a, T b) {
  a = abs(a);
  b = abs(b);
  return (a / gcd(a, b)) * b;
}
template <class T, class X>
inline bool getbit(T a, X i) {
  T t = 1;
  return ((a & (t << i)) > 0);
}
template <class T, class X>
inline T setbit(T a, X i) {
  T t = 1;
  return (a | (t << i));
}
template <class T, class X>
inline T resetbit(T a, X i) {
  T t = 1;
  return (a & (~(t << i)));
}
inline long long getnum() {
  char c = getchar();
  long long num, sign = 1;
  for (; c < '0' || c > '9'; c = getchar())
    if (c == '-') sign = -1;
  for (num = 0; c >= '0' && c <= '9';) {
    c -= '0';
    num = num * 10 + c;
    c = getchar();
  }
  return num * sign;
}
inline long long power(long long a, long long b) {
  long long multiply = 1;
  for (int i = (0); i < (b); i++) {
    multiply *= a;
  }
  return multiply;
}
int n, m, cnt = 0;
vector<int> take[5 * 100002];
set<int> all;
vector<int> forbid[5 * 100002];
void dfs(int u) {
  all.erase(u);
  take[cnt].push_back(u);
  auto it = all.begin();
  while (it != all.end()) {
    int v = *it;
    if (binary_search(forbid[u].begin(), forbid[u].end(), v)) {
      it++;
      continue;
    }
    dfs(v);
    it = all.lower_bound(v);
  }
}
int main() {
  int test, cases = 1;
  scanf("%d%d", &n, &m);
  int u, v;
  for (int i = (0); i < (m); i++) {
    u = getnum();
    v = getnum();
    forbid[u].push_back(v);
    forbid[v].push_back(u);
  }
  for (int i = (1); i < (n + 1); i++)
    all.insert(i), sort(forbid[i].begin(), forbid[i].end());
  for (int i = (1); i < (n + 1); i++) {
    if (all.find(i) != all.end()) {
      cnt++;
      dfs(i);
    }
  }
  cout << cnt << "\n";
  for (int i = (1); i < (cnt + 1); i++) {
    printf("%d ", (int)take[i].size());
    for (int j = (0); j < (take[i].size()); j++) printf("%d ", take[i][j]);
    puts("");
  }
  return 0;
}
