#include <cstdio>
#include <vector>
#include <stack>

using namespace std;

vector<int> vecini[100005];
vector<int> vecinix[100005];
int n, m;
stack<int> S;
vector<vector<int> > sol;
vector<int> solx;
int viz[100005];
int vizx[100005];

void citire(){
    scanf("%d %d", &n, &m);

    int x, y;

    for(int i = 0; i < m; i++){
        scanf("%d %d", &x, &y);
        vecini[x].push_back(y);
        vecinix[y].push_back(x);
    }
}

void dfs(int x){
    vizx[x] = true;
    int l = vecini[x].size();

    S.push(x);

    for(int i = 0; i < l; i++){
        int xx = vecini[x][i];

        if(vizx[xx] == false){
            dfs(vecini[x][i]);
        }
    }
}

void addComponent(int x){
    solx.push_back(x);
    viz[x] = true;

    int l = vecinix[x].size();

    for(int i = 0; i < l; i++){
        int xx = vecinix[x][i];
        if(viz[xx] == false){
            addComponent(xx);
        }
    }
}

void solve(){
    for(int i = 1; i <= n; i++){
        if(viz[i] == false){
            solx.clear();
            addComponent(i);
            sol.push_back(solx);
        }
    }
}

void afisare(){
    int l = sol.size();

    printf("%d\n", l);

    for(int i = 0; i < l; i++, printf("\n")){
        int ll = sol[i].size();

        for(int j = 0; j < ll; j++){
            printf("%d ", sol[i][j]);
        }
    }
}

int main()
{
    freopen("ctc.in", "r", stdin);
    freopen("ctc.out", "w", stdout);

    citire();
    dfs(1);
    solve();
    afisare();

    return 0;
}