rack.cpp: In function 'int main()':
rack.cpp:20:23: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
20 | #define fileio freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
rack.cpp:49:5: note: in expansion of macro 'fileio'
49 | fileio;
| ^~~~~~
rack.cpp:20:57: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
20 | #define fileio freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
rack.cpp:49:5: note: in expansion of macro 'fileio'
49 | fileio;
| ^~~~~~