#include <bits/stdc++.h>

using namespace std;
#define pb push_back
const int N = 1e5 + 5;

int n, m, nr, gasit, dfs_time[N], low[N];
vector<int> G[N], bcc[N];
stack<int> stk;

void get_bcx(int node, int vec) {
    nr++;
    while (!stk.empty() && stk.top() != vec) {
        bcc[nr].pb(stk.top());
        stk.pop();
    }
    bcc[nr].pb(stk.top());
    stk.pop();
    bcc[nr].pb(node);
}

void dfs(int node, int parinte) {
    dfs_time[node] = low[node] = ++gasit;
    stk.push(node);
    for (auto vec : G[node]) {
        if (!dfs_time[vec]) {
            dfs(vec, node);
            low[node] = min(low[node], low[vec]);
            if (low[vec] >= dfs_time[node])
                get_bcx(node, vec);
        }
        else if (vec != parinte)
            low[node] = min(low[node], dfs_time[vec]);
    }
}

int main()
{
    freopen("biconex.in", "r", stdin);
    freopen("biconex.out", "w", stdout);
    cin.tie(0)->sync_with_stdio(0);
    cin >> n >> m;
    for (int i = 1; i <= m; i++) {
        int a, b;
        cin >> a >> b;
        G[a].pb(b);
        G[b].pb(a);
    }
    for (int i = 1; i <= n; i++) {
        if (!dfs_time[i])
            dfs(i, 0);
    }
    cout << nr << '\n';
    for (int i = 1; i <= nr; i++) {
        for (auto x : bcc[i])
            cout << x << ' ';
        cout << '\n';
    }
    return 0;
}