#include <bits/stdc++.h>

using namespace std;

ifstream f("biconex.in");
ofstream g("biconex.out");

const int NMAX = 1e5;
vector<int> G[NMAX + 1];
int low[NMAX + 1], niv[NMAX + 1];
stack<pair<int, int>> st;
set<int> cb[NMAX + 1];
int cnt;

void dfs(int node, int dad) {
    niv[node] = niv[dad] + 1;
    low[node] = niv[node];
    for(auto next : G[node]) {
        if(next == dad) {
            continue;
        }
        if(niv[next]) {
            low[node] = min(low[node], niv[next]);
        } else {
            st.push({node, next});
            dfs(next, node);
            low[node] = min(low[node], low[next]);
            if(low[next] >= niv[node]) {
                cnt++;
                while(true) {
                    auto it = st.top();
                    st.pop();
                    cb[cnt].insert(it.first);
                    cb[cnt].insert(it.second);
                    if(it.first == node && it.second == next) {
                        break;
                    }
                }
            }
        }
    }
}

int main() {
    int n, m;
    f >> n >> m;
    while(m--) {
        int x, y;
        f >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    dfs(1, 0);
    g << cnt << '\n';
    for(int i = 1; i <= cnt; i++) {
        for(auto it : cb[i]) {
            g << it << ' ';
        }
        g << '\n';
    }
    return 0;
}