Compilare: user.cpp: In function ‘void build()’: user.cpp:43: warning: unused variable ‘x’ user.cpp: In function ‘int main()’: user.cpp:102: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:103: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:105: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:109: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:114: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:115: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result