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

using ll = long long;
using Vi = vector<int>;
using Vl = vector<ll>;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;

constexpr int I_INF = numeric_limits<int>::max();
constexpr ll L_INF = numeric_limits<ll>::max();

template <typename T1, typename T2>
inline bool chmin(T1& a, const T2& b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <typename T1, typename T2>
inline bool chmax(T1& a, const T2& b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

class Prints {
private:
    class __Prints {
    public:
        __Prints(const char* sep, const char* term) : sep(sep), term(term) {}
        template <class... Args>
        void operator()(const Args&... args) const { print(args...); }

    private:
        const char *sep, *term;
        void print() const { std::cout << term; }
        void print_rest() const { std::cout << term; }
        template <class T, class... Tail>
        void print(const T& head, const Tail&... tail) const { std::cout << head, print_rest(tail...); }
        template <class T, class... Tail>
        void print_rest(const T& head, const Tail&... tail) const { std::cout << sep << head, print_rest(tail...); }
    };

public:
    Prints() {}
    __Prints operator()(const char* sep = " ", const char* term = "\n") const { return __Prints(sep, term); }
};

Prints prints;

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

using Graph = std::vector<std::vector<int>>;
int scc(std::vector<int>& res, const Graph& g) {
    const int sz = static_cast<int>(g.size());
    Graph rg(sz);
    for (int i = 0; i < sz; i++) {
        for (const auto& v : g[i]) {
            rg[v].emplace_back(i);
        }
    }
    vector<int> vs;
    vector<bool> used(sz, false);
    auto dfs1 = [&g, &used, &vs](auto&& self, int idx) -> void {
        used[idx] = true;
        for (const auto& v : g[idx]) {
            if (!used[v]) self(self, v);
        }
        vs.emplace_back(idx);
    };
    auto dfs2 = [&rg, &res, &used](auto&& self, int idx, int k) -> void {
        used[idx] = true;
        res[idx] = k;
        for (const auto& v : rg[idx]) {
            if (!used[v]) self(self, v, k);
        }
    };
    res.resize(sz);
    for (int i = 0; i < sz; i++) {
        if (!used[i]) dfs1(dfs1, i);
    }
    used.assign(sz, false);
    int ord = 0;
    for (int i = sz - 1; i >= 0; i--) {
        if (!used[vs[i]]) dfs2(dfs2, vs[i], ord++);
    }
    return ord;
}

void solve() {
    int N, M;
    cin >> N >> M;
    Graph g(N);
    for (ll i = 0; i < M; i++) {
        int a, b;
        cin >> a >> b;
        g[a].emplace_back(b);
    }

    Vi scc_res;
    int scc_sz = scc(scc_res, g);
    vector<Vi> res(scc_sz);
    for (ll i = 0; i < N; i++) {
        res[scc_res[i]].emplace_back(i);
    }

    prints()(scc_sz);
    for (ll i = 0; i < scc_sz; i++) {
        prints("", " ")(res[i].size());
        for (auto v : res[i]) {
            prints("", " ")(v);
        }
        prints()();
    }
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

int main() {
#ifdef FASTIO
    cin.tie(nullptr), cout.tie(nullptr);
    ios::sync_with_stdio(false);
#endif
#ifdef FILEINPUT
    ifstream ifs("./in_out/input.txt");
    cin.rdbuf(ifs.rdbuf());
#endif
#ifdef FILEOUTPUT
    ofstream ofs("./in_out/output.txt");
    cout.rdbuf(ofs.rdbuf());
#endif
    cout << setprecision(18) << fixed;
    solve();
    cout << flush;
    return 0;
}


Measured memory_bytes: 56392