lanterna.cpp: In function 'int main()': lanterna.cpp:216: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result lanterna.cpp:217: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result lanterna.cpp:220: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result lanterna.cpp:223: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result lanterna.cpp:226: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result lanterna.cpp:254: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result