cub2.cpp: In function 'int main()': cub2.cpp:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result cub2.cpp:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result cub2.cpp:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result cub2.cpp:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result cub2.cpp:45: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result cub2.cpp:54: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result cub2.cpp:32: warning: 'nr' may be used uninitialized in this function