joi2019_ho_t4.cpp: In function 'int main()':
joi2019_ho_t4.cpp:3:19: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
      |            ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
joi2019_ho_t4.cpp:27:45: note: in expansion of macro 'fo'
   27 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~
joi2019_ho_t4.cpp:3:63: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
      |                                                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
joi2019_ho_t4.cpp:27:45: note: in expansion of macro 'fo'
   27 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~