answer.code: In function ‘int min_cardinality(int)’:
answer.code:15:9: error: ‘move_inside’ was not declared in this scope
   15 |         move_inside(front);
      |         ^~~~~~~~~~~
answer.code:22:23: error: ‘press_button’ was not declared in this scope
   22 |             int res = press_button();
      |                       ^~~~~~~~~~~~
answer.code:24:17: error: ‘move_outside’ was not declared in this scope
   24 |                 move_outside(current_pos);
      |                 ^~~~~~~~~~~~
answer.code:32:13: error: ‘move_outside’ was not declared in this scope
   32 |             move_outside(erased[i]);
      |             ^~~~~~~~~~~~