#include <fstream>
#include <vector>
#include <stack>
#include <bitset>
using namespace std;

ifstream fin("ctc.in");
ofstream fout("ctc.out");

#define MaxN 100001
#define pb push_back
int n, m;
int nr = 0;

vector<int> G[MaxN], G_reversed[MaxN], Solution[MaxN], ap(MaxN, -1);
bitset<MaxN> seen;
stack<int> st;

void Dfs(int);
void Dfs_reversed(int);

int main()
{
    fin >> n >> m;

    for ( int i = 1, a, b; i <= m; ++i )
    {
        fin >> a >> b;
        G[a].pb(b);
        G_reversed[b].pb(a);
    }

    for ( int i = 1; i <= n; ++i )
        if ( !seen[i] )
            Dfs(i);

    seen.reset();

    while( !st.empty() )
    {
        int nod = st.top();
        if ( ap[nod] == -1 )
            {
            nr++;
            Dfs_reversed(nod);
            }
        st.pop();
    }

    for ( int i = 1; i <= n; ++i )
        Solution[ap[i]].pb(i);

    fout << nr << '\n';

    for ( int i = 1; i <= n; ++i )
    {
        for ( auto p : Solution[i] )
            fout << p << ' ';
        fout << '\n';
    }


    fin.close();
    fout.close();
    return 0;
}

void Dfs(int i)
{
    seen[i] = 1;
    for ( auto p : G[i] )
        if ( !seen[p] )
            Dfs(p);
    st.push(i);
}

void Dfs_reversed(int i)
{
    ap[i] = nr;
    for ( auto p : G_reversed[i] )
        if ( ap[p] == -1 )
            Dfs_reversed(p);
}