#include <bits/stdc++.h>
#define u64 unsigned long long
using namespace std;

mt19937_64 rnd(chrono::steady_clock::now().time_since_epoch().count());

const int N = 2e5 + 5;

int n, m, tot = 1, h[N], tid[N], id[N];
bool vis[N], visr[N], cut[N], used[N];
u64 val[N][10];
vector<int> ne[N];
vector<vector<int>> ans;

struct E {
	int v, nxt;
} e[N * 2];

void add(int u, int v) {
	e[++tot].v = v;
	e[tot].nxt = h[u];
	h[u] = tot;
}

void dfs(int u, int fr) {
	vis[u] = 1;
	for (int i = h[u]; i; i = e[i].nxt) {
		if ((i ^ 1) == fr) {
			continue;
		}
		int v = e[i].v;
		if (!vis[v]) {
			ne[u].emplace_back(v);
			tid[v] = i >> 1;
			dfs(v, i);
		} else if (!visr[i >> 1]) {
			visr[i >> 1] = 1;
			for (int j = 0; j < 10; j++) {
				u64 w = rnd();
				val[i >> 1][j] = w;
				val[tid[u]][j] ^= w;
				val[tid[v]][j] ^= w;
			}
		}
	}
}

void getval(int u) {
	for (int v : ne[u]) {
		getval(v);
		for (int j = 0; j < 10; j++) {
			val[tid[u]][j] ^= val[tid[v]][j];
		}
	}
}

bool cmp(int i, int j) {
	for (int k = 0; k < 10; k++) {
		if (val[i][k] != val[j][k]) {
			return val[i][k] < val[j][k];
		}
	}
	return 0;
}

bool chk(int i, int j) {
	bool res = 1;
	for (int k = 0; k < 10; k++) {
		res &= val[i][k] == val[j][k];
	}
	return res;
}

void find(int u, vector<int> &a) {
	used[u] = 1;
	a.emplace_back(u);
	for (int i = h[u]; i; i = e[i].nxt) {
		if (cut[i >> 1]) {
			continue;
		}
		int v = e[i].v;
		if (!used[v]) {
			find(v, a);
		}
	}
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> n >> m;
	for (int i = 1; i <= m; i++) {
		int u, v;
		cin >> u >> v;
		u++, v++;
		add(u, v);
		add(v, u);
	}
	for (int i = 1; i <= n; i++) {
		if (vis[i]) {
			continue;
		}
		dfs(i, 0);
		getval(i);
	}
	for (int i = 1; i <= m; i++) {
		id[i] = i;
	}
	sort(id + 1, id + m + 1, cmp);
	for (int i = 1; i <= m; i++) {
		int l = i;
		while (i < m && chk(id[i], id[i + 1])) {
			i++;
		}
		bool ok = 1;
		if (l == i) {
			for (int j = 0; j < 10; j++) {
				ok &= !val[id[i]][j];
			}
		}
		if (ok) {
			for (int j = l; j <= i; j++) {
				cut[id[j]] = 1;
			}
		}
	}
	for (int u = 1; u <= n; u++) {
		if (!used[u]) {
			vector<int> a;
			find(u, a);
			ans.emplace_back(a);
		}
	}
	cout << ans.size() << '\n';
	for (auto &a : ans) {
		cout << a.size() << ' ';
		for (int u : a) {
			cout << u - 1 << ' ';
		}
		cout << '\n';
	}

	return 0;
}