radio.cpp: In function 'int main()': radio.cpp:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result radio.cpp:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result radio.cpp:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result radio.cpp:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result radio.cpp:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result radio.cpp:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result