#include <fstream>
#include <vector>
#include <bitset>
#include <queue>
#include <algorithm>
#include <utility>
#include <cstring>
#include <string>
#include <stack>
#include <deque>
#include <iomanip>
#include <set>
#include <map>
#include <cassert>
#include <ctime>
#include <list>
#include <iomanip>

using namespace std;

string file = "ctc";

ifstream cin( (file + ".in").c_str() );
ofstream cout( (file + ".out").c_str() );

const int MAXN = 100005;
const int oo = (1<<31)-1;

typedef vector<int> Graph[MAXN];
typedef vector<int> :: iterator It;

const inline int min(const int &a, const int &b) { if( a > b ) return b;   return a; }
const inline int max(const int &a, const int &b) { if( a < b ) return b;   return a; }
const inline void Get_min(int &a, const int b)    { if( a > b ) a = b; }
const inline void Get_max(int &a, const int b)    { if( a < b ) a = b; }

struct ClassComp {
    inline bool operator () (const int &a, const int &b) const {
        return a > b;
    }
};

Graph G, Gt;
int N, M;
bitset<MAXN> Used;
vector<int> Tsort;

inline void DFs(int Node) {
    Used[Node] = true;
    for(It it = G[Node].begin() , fin = G[Node].end(); it != fin ; ++ it)
        if(!Used[*it])
            DFs(*it);
    Tsort.push_back(Node);
}

inline void DF(int Node) {
    Used[Node] = true;
    cout << Node << ' ';
    for(It it = Gt[Node].begin(), fin = Gt[Node].end() ; it != fin ; ++ it)
        if(!Used[*it])
            DF(*it);
}

inline void Kosaraju() {
    for(int i = 1 ; i <= N ; ++ i)
        if(!Used[i])
            DFs(i);
    Used.reset();
    int SCC = 0;
    cout << "                      \n";
    for(vector<int>::reverse_iterator it = Tsort.rbegin(), fin = Tsort.rend() ; it != fin ; ++ it)
        if(!Used[*it]) {
            ++ SCC;
            DF(*it);
            cout << '\n';
        }
    cout.seekp(0, ios::beg);
    cout << SCC;
}

int main() {
    cin >> N >> M;
    for(int i = 1 ; i <= M ; ++ i) {
        int x, y;
        cin >> x >> y;
        G[x].push_back(y);
        Gt[y].push_back(x);
    }
    Kosaraju();
    cin.close();
    cout.close();
    return 0;
}