#include <fstream>
#include <vector>
#include <cstring>
#define Nmax 100002
#define Bmax 100000
using namespace std;

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

int n,p,m,a,b;
char buffer[Bmax+2];
vector<int> H,v[Nmax],v2[Nmax];
vector<vector<int> > ans;
bool uz[Nmax];

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);
    }
    H.push_back(nod);
}

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


int main()
{
    f.read(buffer,Bmax);

    read(n);read(m);
    for (int i=1;i<=m;i++){
        read(a);read(b);
        v[a].push_back(b);
        v2[b].push_back(a);
    }

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

    memset(uz,0,sizeof(uz));
    for (auto it = H.rbegin();it!=H.rend();it++){
            if (!uz[*it]){
                ans.push_back(*new vector<int>);
                dfs2(*it);
            }
    }

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


    return 0;
}