#include 
#include 
#include 
#include 
using namespace std;
typedef long long ll;
int n, m;
vector graph[1005], rev_graph[1005];
stack st;
bool visited[1005];

void dfs(int node) {
    visited[node] = true;
    for(int i = 0; i < graph[node].size(); i++) {
        int sosed = graph[node][i];
        if(!visited[sosed])
            dfs(sosed);
    }
    st.push(node);
}
void rev_dfs(int node) {
    visited[node] = true;
    cout << node << " ";
    for(int i = 0; i < rev_graph[node].size(); i++) {
        int sosed = rev_graph[node][i];
        if(!visited[sosed]) {
            rev_dfs(sosed);
        }
    }
}
int main() {
    ios_base::sync_with_stdio(false);
    cin >> n >> m;
    
    for(int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        graph[a].push_back(b);
        rev_graph[b].push_back(a);
    }
    memset(visited, false, sizeof visited);
    for(int i = 0; i < n; i++) {
        if(!visited[i]) {
            dfs(i);
        }
    }
    memset(visited, false, sizeof visited);
    while(!st.empty()) {
        int node = st.top();
        if(!visited[node]) {
            rev_dfs(node);
            cout << endl;
        }
        st.pop();
    }
    return 0;
}