#include <fstream>
#include <vector>
#include <cstring>
#define Nmax 100002
#define Bmax 100002
using namespace std;

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

int n,m,p;
char buffer[Bmax];
bool uz[Nmax];
vector<int> v[Nmax],st,res2,v2[Nmax];
vector<vector<int> > res;

bool digit(int x) {if (x>='0' && x<='9') return 1;return 0;}

void read(int &x){
    x = 0;
    while (!digit(buffer[p])){
        p++;
        if (p==Bmax) f.read(buffer,Bmax), p = 0;
    }
    while (digit(buffer[p])){
        x = x*10+buffer[p]-'0';
        p++;
        if (p==Bmax) f.read(buffer,Bmax),p = 0;
    }
}

void dfs(int nod){
    uz[nod] = 1;
    for (auto it : v[nod]){
        if (uz[it]) continue;
        dfs(it);
    }
    st.push_back(nod);
}

void dfs2(int nod){
    res2.push_back(nod);
    uz[nod] = 1;
    for (auto it : v2[nod]){
        if (uz[it]) continue;
        dfs2(it);
    }
}

int main()
{
    f.read(buffer,Bmax);
    read(n);
    read(m);
    for (int i=1;i<=m;i++){
        int x,y;
        read(x);
        read(y);
        v[x].push_back(y);
        v2[y].push_back(x);
    }

    for (int i=1;i<=n;i++)
        if (!uz[i]) dfs(i);

    memset(uz,0,sizeof(uz));
    for (int i=n-1;i>=0;i--){
        res2.clear();
        if (!uz[st[i]]){
            dfs2(st[i]);
            res.push_back(res2);
        }
    }

    g<<res.size()<<'\n';
    for (auto it : res){
        for (auto it2 : it)
            g<<it2<<' ';
        g<<'\n';
    }


    return 0;
}