#include <bits/stdc++.h>
using namespace std;

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

vector < int > v[100005];
int n,m,x,y;
int disc[100005],low[100005],parent[100005],ap[100005],child[100005];
vector < vector < int > > comps;
vector < int > bcnx;
int timp;
stack < pair < int , int > > st;

void read() {
    f >> n >> m;
    for (int i=1;i<=m;i++) {
        f >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
}

void create_comp(int a, int b) {
    x = st.top().first; y=st.top().second;
    while (x!=a && y!=b) {
        bcnx.push_back(y);
        st.pop();
        x = st.top().first; y=st.top().second;
    }
    bcnx.push_back(x);
    bcnx.push_back(y);
    st.pop();
    comps.push_back(bcnx);
    bcnx.clear();
}

void dfs(int nod) {
    timp++;
    low[nod]=timp; disc[nod]=timp;
    for (auto k:v[nod]) {
        if (disc[k]==0) {
            st.push({nod,k});
            child[nod]++;
            parent[k] = nod;
            dfs(k);
            low[nod] = min(low[nod],low[k]);
            if (low[k]>=disc[nod]) {
                ap[nod]=1;
                create_comp(nod,k);
            }
        }
        else if (parent[nod]!=k) {
            low[nod] = min(low[nod],disc[k]);
        }
    }
}

void solve() {
    for (int i=1;i<=n;i++) {
        if (disc[i]==0) {
            dfs(i);
        }
    }

}

void show() {
    g << comps.size() << '\n';
    for (int i=0;i<comps.size();i++) {
        for (int k:comps[i]) {
            g << k << " ";
        }
        g << '\n';
    }
}

int main()
{
    read();
    solve();
    show();
    return 0;
}