sotron.cpp: In function 'void read()': sotron.cpp:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sotron.cpp:11: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sotron.cpp:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sotron.cpp: In function 'void write()': sotron.cpp:60: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result