/*
灏忓簾鐗╋紝杩欓兘涓嶄細 /cf
*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mp make_pair
#define inf (ll)1e9
#define pii pair <ll, ll>
#define fr first
#define se second
const ll mod = 1e9 + 7;
char buf[1 << 21], *p1 = buf, *p2 = buf;
#define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1 << 18, stdin), p1 == p2) ? EOF : *p1++)
inline ll read() {
	ll x = 0, f = 1;
	char ch = getchar();
	while(ch < '0' || ch > '9') f = ((ch == '-') ? -1 : f), ch = getchar();
	while(ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
	return x * f;
}
inline void write(ll x) {
	if(x < 0) x = -x, putchar('-');
	if(x >= 10) write(x / 10);
	putchar(x % 10 + '0');
}
ll n, m;
vector <pii> G[200005];
ll dfn[200005], low[200005], tot;
ll sta[200005], top;

ll cnt;
vector <ll> V[200005];
map <pii, ll> M;
inline void Tarjan(ll x, ll fa) {
	dfn[x] = low[x] = ++tot;
	sta[++top] = x;
	for(auto y : G[x]) {
		if(y.se == fa) continue;
		if(!dfn[y.fr]) {
			Tarjan(y.fr, y.se);
			if(low[y.fr] >= dfn[x]) {
				if(sta[top] == y.fr && M[mp(x, y.fr)] < 2) continue;
				cnt++, V[cnt].push_back(x), V[cnt].push_back(y.fr);
				while(sta[top] != y.fr) V[cnt].push_back(sta[top--]);
				top--;
			}
			low[x] = min(low[x], low[y.fr]);
		}
		else low[x] = min(low[x], dfn[y.fr]);
	}
}
int main() {
//	freopen(".in", "r", stdin);
//	freopen(".out", "w", stdout);
	n = read(), m = read();
	for(ll i = 1; i <= m; i++) {
		ll u = read() + 1, v = read() + 1;
		G[u].push_back(mp(v, i));
		G[v].push_back(mp(u, i));
		M[mp(u, v)]++, M[mp(v, u)]++;
	}
	for(ll i = 1; i <= n; i++) if(!dfn[i]) Tarjan(i, 0);
	write(cnt), putchar('\n');
	for(ll i = 1; i <= cnt; i++) {
		write((ll)V[i].size()), putchar(' ');
		for(auto j : V[i]) write(j - 1), putchar(' ');
		putchar('\n');
	}
	return 0;
}
/*
*/