/in/foo.cc:7:6: error: 'vector' in namespace 'std' does not name a template type
 std::vector<int> adj[1010];
      ^~~~~~
/in/foo.cc: In function 'int Dfs(const int&)':
/in/foo.cc:13:25: error: 'adj' was not declared in this scope
   for (register int i : adj[cur]) {
                         ^~~
/in/foo.cc: In function 'int main(int, const char**)':
/in/foo.cc:25:7: error: 'adj' was not declared in this scope
       adj[i].push_back(_);
       ^~~