#include<cstdio>
#include<set>
#include<stack>
#include<vector>
#include<algorithm>
 
using namespace std;
 
const int Nmax = 200001;
 
int lev[Nmax], low[Nmax], T[Nmax], N, M, K, cnt;
vector<int> G[Nmax];
stack<pair<int, int> > S;
set<int> sol[Nmax];

void component (int x, int y) {
	
	int a, b;
    
	++K;
	do {
        a = S.top().first; b = S.top().second; 
		S.pop();
        sol[K].insert(a); sol[K].insert(b);
    } while(a != x && b != y);
}

void dfs(int node) {
	
    int son;
    vector <int>::iterator it;
	
    lev[node] = low[node] = ++cnt;
    for(it=G[node].begin(); it!=G[node].end(); it++) {
        son = *it;
		
		if(son == T[node])
			continue;
		
        if(!lev[son]) {
			S.push(make_pair(node, son));
			T[son] = node; 
			dfs(son);
			
			low[node] = min(low[node], low[son]);
			if(lev[node]<=low[son])
				component(node, son);
		}
		else
			low[node] = min(low[node], lev[son]);
    }
}
 
void input () {
	
	freopen ("biconex.in", "r", stdin);
	
	scanf ("%d %d", &N, &M);
	
	int i, x, y;
    
	for(i=1; i<=M; i++) {
        scanf("%d %d",&x,&y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
}
 
void output () {
	
    freopen ("biconex.out", "w", stdout);
	
	int i;
	set<int>:: iterator it;
	
    printf("%d\n", K);
    for(i=1; i<=K; i++) {
        for(it=sol[i].begin(); it!=sol[i].end(); it++)
            printf("%d ", *it);
        printf("\n");
    }
}

int main () {
	
	input ();
	
	dfs (1);
	
	output ();
	
	return 0;
}