/in/foo.cc: In function 'int main()':
/in/foo.cc:21:2: error: 'cin' was not declared in this scope
  cin >> n >> k;
  ^~~
/in/foo.cc:34:3: error: 'cout' was not declared in this scope
   cout << person[i].pos << endl;
   ^~~~
/in/foo.cc:34:28: error: 'endl' was not declared in this scope
   cout << person[i].pos << endl;
                            ^~~~