trmv.cpp: In function 'void read_data()': trmv.cpp:21: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result trmv.cpp:22: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result trmv.cpp:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result trmv.cpp:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result trmv.cpp:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result trmv.cpp:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result trmv.cpp:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result