fillmat.cpp: In function 'int main()': fillmat.cpp:58: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result fillmat.cpp:59: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result fillmat.cpp:61: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result fillmat.cpp:65: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result fillmat.cpp:66: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result