#include <bits/stdc++.h>

using namespace std;

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

const int N = 1e5 + 5;
int n, m, nr;
bool viz[N];
vector <int> v[N], rev[N], ans[N], topsort;

void dfs(int nod){
    viz[nod] = 1;
    for(auto vecin : v[nod]){
        if(!viz[vecin])
            dfs(vecin);
    }
    topsort.push_back(nod);
}

void dfs2(int nod){
    viz[nod] = 1;
    for(auto vecin : rev[nod]){
        if(!viz[vecin])
            dfs2(vecin);
    }
    ans[nr].push_back(nod);
}

int main(){
    in >> n >> m;
    for(int i = 1; i <= m; i++){
        int x, y;
        in >> x >> y;
        v[x].push_back(y);
        rev[y].push_back(x);
    }

    for(int i = 1; i <= n; i++){
        if(!viz[i])
            dfs(i);
    }
    reverse(topsort.begin(), topsort.end());

    for(auto it : topsort)
        cout << it << " ";

    for(int i = 0; i <= n; i++)
        viz[i] = 0;
    for(auto nod : topsort){
        if(!viz[nod]){
            nr++;
            dfs2(nod);
        }
    }

    out << nr << '\n';
    for(int i = 1; i <= n; i++){
        for(auto it : ans[i]){
            out << it << " ";
        }
        if(!ans[i].empty())
            out << '\n';
    }
    return 0;
}