/in/foo.cc: In function 'int main()':
/in/foo.cc:10:2: error: 'cin' was not declared in this scope
  cin >> n;
  ^~~
/in/foo.cc:10:2: note: suggested alternative: 'main'
  cin >> n;
  ^~~
  main
/in/foo.cc:16:4: error: 'cout' was not declared in this scope
    cout << stu[i].second.first << ' ' << stu[i].first << ' ' << stu[i].second.second << endl;
    ^~~~
/in/foo.cc:16:89: error: 'endl' was not declared in this scope
    cout << stu[i].second.first << ' ' << stu[i].first << ' ' << stu[i].second.second << endl;
                                                                                         ^~~~
/in/foo.cc:16:89: note: suggested alternative: 'enum'
    cout << stu[i].second.first << ' ' << stu[i].first << ' ' << stu[i].second.second << endl;
                                                                                         ^~~~
                                                                                         enum