qvect.cpp: In function 'int main()': qvect.cpp:28: warning: left-hand operand of comma has no effect qvect.cpp:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result qvect.cpp:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result qvect.cpp:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result qvect.cpp:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result qvect.cpp:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result qvect.cpp:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result