#include #include #include #include #include #include #include #include using namespace std; const int maxn = 1e5 + 10; int n, m; vector graph[maxn], reversed_graph[maxn]; bool visited[maxn]; stack st; void topological_sort(int node) { visited[node] = true; for(int i = 0; i < (int) graph[node].size(); i++) { int neighbour = graph[node][i]; if(!visited[neighbour]) { topological_sort(neighbour); } } st.push(node); } void dfs(int node) { cout << node + 1 << " " ; visited[node] = true; for(int i = 0; i < (int) reversed_graph[node].size(); i++) { int neighbour = reversed_graph[node][i]; if(!visited[neighbour]) { dfs(neighbour); } } } int main() { cin >> n >> m; for(int i = 0; i < m; i++) { int a, b; cin >> a>> b; a--; b--; graph[a].push_back(b); reversed_graph[b].push_back(a); } memset(visited, false, sizeof visited); for(int i = 0; i < n; i++) { if(!visited[i]) { topological_sort(i); } } memset(visited, false, sizeof visited); while(!st.empty()) { int node = st.top(); st.pop(); if(!visited[node]) { dfs(node); cout << endl; } } return 0; }