Compilare: user.cpp: In function ‘int main()’: user.cpp:30: warning: unused variable ‘k’ user.cpp:30: warning: unused variable ‘a’ user.cpp:30: warning: unused variable ‘b’ user.cpp:30: warning: unused variable ‘a2’ user.cpp:30: warning: unused variable ‘b2’ user.cpp:27: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:28: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result