#include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <set>
#include <map>
#include "optimization.h"
#include <unordered_map>
using namespace std;
vector<vector<int>> tree;

int n, e;
map<pair<int, int>, int> mem;
vector<int> time_;
vector<int> min_time;
stack<int> stack_;
int T = 0;
vector<vector<int>> result;
multiset<pair<int,int>> mark;
void relax(int &a, int &b) {
    if (b < a) {
        a = b;
    }
}

void dfs(int root, int parent) {
    stack_.push(root);
    time_[root] = min_time[root] = ++T;
    for (auto x: tree[root]) {
        if (x == parent) continue;
        if (!time_[x]) {
            int stack_lvl = stack_.size();
            dfs(x, root);
            relax(min_time[root], min_time[x]);
            if (min_time[x] > time_[root] && (mark.count({min(root,x), max(root,x)}) == 1)) {
                vector<int> tmp;
                while (stack_.size() > stack_lvl) {
                    tmp.push_back(stack_.top());
                    stack_.pop();
                }
                if (!tmp.empty()) result.push_back(tmp);
//                result.insert(y);
            }
        } else {
            relax(min_time[root], time_[x]);
        }
    }
}


int main() {
//    cin >> n >> e;
    n = readInt();
    e = readInt();
//    mark.resize(n+1, vector<int>(n+1, 0));
    tree.resize(n + 1);
    time_.resize(n + 1, 0);
    min_time.resize(n + 1);
    for (int i = 1; i <= e; i++) {
        int a, b;
//        cin >> a >> b;
        a = readInt();
        b = readInt();
        if (a > b) {
            swap(a, b);
        }
        mark.insert({a,b});
        tree[a].push_back(b);
        tree[b].push_back(a);
    }

    for (int v = 1; v <= n; v++) {
        int stack_lvl = stack_.size();
        if (time_[v] == 0) { dfs(v, 0); }
        vector<int> tmp;
        while (stack_.size() > stack_lvl) {
            tmp.push_back(stack_.top());
            stack_.pop();
        }
        if (!tmp.empty()) {
            result.push_back(tmp);
        }
    }
    for (auto &x : result){
        sort(x.begin(), x.end());
    }
    sort(result.begin(), result.end());
//    cout << result.size() << '\n';
    writeInt(result.size(), '\n');

    for (auto &x: result) {
//        cout << x << '\n';
//        sort(x.begin(), x.end());
        for (auto &y: x) {
            writeInt(y, ' ');
//            cout << y << " ";
        }
        writeChar('\n');
//cout << '\n';
    }
}