arbsum.cpp: In function 'int main()': arbsum.cpp:23: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result arbsum.cpp:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result arbsum.cpp:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result arbsum.cpp:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result arbsum.cpp:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result