#include <fstream>

using namespace std;
ifstream fin("ctc.in");
ofstream fout("ctc.out");
int n, m, a[2][200005], atr[2][200005], pluss[100005], minuss[100005], start[100005], starttr[100005], viz[100005], nr, v[100005];
void initp();
void initm();
void dfp(int nod);
void dfm(int nod);
void plusminus(int caz);
int main()
{
    int i, x, y, k = 0, k1 = 0;
    fin >> n >> m;
    for (i = 1; i <= m; i++) {
        fin >> x >> y;
        k++;
        a[0][k] = y;
        a[1][k] = start[x];
        start[x] = k;
        k1++;
        atr[0][k1] = x;
        atr[1][k1] = starttr[y];
        starttr[y] = k1;
    }
    plusminus(1);
    fout << nr << "\n";
    for (i = 1; i <= n; i++)
        v[i] = 0;
    plusminus(2);
    return 0;
}
void initp()
{
    for (int i = 1; i <= n; i++)
        viz[i] = pluss[i] = 0;
}
void initm()
{
    for (int i = 1; i <= n; i++)
        viz[i] = minuss[i] = 0;
}
void dfp(int nod)
{
    int x;
    pluss[nod] = 1;
    viz[nod] = 1;
    x = start[nod];
    while (x) {
        if (viz[a[0][x]] == 0)
            dfp(a[0][x]);
        x = a[1][x];
    }
}
void dfm(int nod)
{
    int x;
    minuss[nod] = 1;
    viz[nod] = 1;
    x = starttr[nod];
    while (x) {
        if (viz[atr[0][x]] == 0)
            dfm(atr[0][x]);
        x = atr[1][x];
    }
}
void plusminus(int caz)
{
    int i, j;
    for (i = 1; i <= n; i++)
        if (v[i] == 0) {
            v[i] = 1;
            nr++;
            initp();
            dfp(i);
            initm();
            dfm(i);
            for (j = 1; j <= n; j++)
                if (pluss[j] == minuss[j]) {
                    v[j] = nr;
                    if (caz == 2)
                        fout << j << " ";
                }
            if (caz == 2)
                fout << "\n";
        }
}