#include <iostream>
#include <fstream>
#include <vector>
#define NMAX 100002
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");

struct path {
    int a,b;
} aux;

int n,m,biconex,id,children;
int ids[NMAX],low[NMAX];
bool visited[NMAX],articulation[NMAX];
vector <int> g[NMAX],ans[NMAX];
vector <path> Stack;

void dfs(int node, int from = -1) {
    visited[node]=true;
    ids[node]=low[node]=id++;
    for(int i=0; i<g[node].size(); i++) {
        int to=g[node][i];
        if(!visited[to]) {
            aux.a=node;
            aux.b=to;
            Stack.push_back(aux);

            if(from==-1)
                children++;
            dfs(to,node);
            low[node]=min(low[node],low[to]);

            if(ids[node]<=low[to]) {
                biconex++;
                articulation[node]=true;
                while(Stack.back().a!=node) {
                    ans[biconex].push_back(Stack.back().b);
                    Stack.pop_back();
                }
                ans[biconex].push_back(to);
                ans[biconex].push_back(node);
                Stack.pop_back();
            }
        }
        if(visited[to]==true && from!=to)
            low[node]=min(low[node],ids[to]);
    }
}

int main() {
    fin>>n>>m;
    for(int i=1; i<=m; i++) {
        int x,y;
        fin>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }

    for(int i=1; i<=n; i++)
        if(!visited[i]) {
            children=0,id=1;
            dfs(i);
            articulation[i] = children>1;
        }

    for(int i=0; i<Stack.size(); i++)
        cout<<Stack[i].a<<" "<<Stack[i].b<<"\n";

    fout<<biconex<<"\n";
    for(int i=1; i<=biconex; i++) {
        for(int j=0; j<ans[i].size(); j++)
            fout<<ans[i][j]<<" ";
        fout<<"\n";
    }
    return 0;
}