Compilare: user.cpp: In function ‘void read()’: user.cpp:14: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘int ok(int)’: user.cpp:34: warning: comparison between signed and unsigned integer expressions