Compilare: user.cpp: In member function ‘void big_int::add(big_int)’: user.cpp:34: warning: comparison between signed and unsigned integer expressions user.cpp: In member function ‘void big_int::substract(big_int)’: user.cpp:49: warning: comparison between signed and unsigned integer expressions user.cpp: In member function ‘void kfib::read()’: user.cpp:88: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result